BELGRADE, Serbia — When Covid-19 reached Eastern Europe in the spring of 2020, a Serbian journalist reported a severe shortage of masks and other protective equipment. She was swiftly arrested, thrown in a windowless cell and charged with inciting panic.

The journalist, Ana Lalic, was quickly released and even got a public apology from the government in what seemed like a small victory against old-style repression by Serbia’s authoritarian president, Aleksandar Vucic.

But Ms. Lalic was then vilified for weeks as a traitor by much of the country’s news media, which has come increasingly under the control of Mr. Vucic and his allies as Serbia adopts tactics favored by Hungary and other states now in retreat from democracy across Europe’s formerly communist eastern fringe.

“For the whole nation, I became a public enemy,” she recalled.

Serbia no longer jails or kills critical journalists, as happened under the rule of Slobodan Milosevic in the 1990s. It now seeks to destroy their credibility and ensure few people see their reports.

The muting of critical voices has greatly helped Mr. Vucic — and also the country’s most well-known athlete, the tennis star Novak Djokovic, whose visa travails in Australia have been portrayed as an intolerable affront to the Serb nation. The few remaining outlets of the independent news media mostly support him but take a more balanced approach.

Across the region, from Poland in the north to Serbia in the south, Eastern Europe has become a fertile ground for new forms of censorship that mostly eschew brute force but deploy gentler yet effective tools to constrict access to critical voices and tilt public opinion — and therefore elections — in favor of those in power.

Television has become so biased in support of Mr. Vucic, according to Zoran Gavrilovic, the executive director of Birodi, an independent monitoring group, that Serbia has “become a big sociological experiment to see just how far media determines opinion and elections.”

Serbia and Hungary — countries in the vanguard of what V-Dem Institute, a Swedish research group, described last year as a “global wave of autocratization” — both hold general elections in April, votes that will test whether media control works.

A recent Birodi survey of news reports on Serbian television found that over a three-month period from September, Mr. Vucic was given more than 44 hours of coverage, 87 percent of it positive, compared with three hours for the main opposition party, 83 percent of which was negative.

Nearly all of the negative coverage of Mr. Vucic appeared on N1, an independent news channel that broadcast Ms. Lalic’s Covid-19 reports. But a bitter war for market share is playing out between the cable provider that hosts N1 — Serbian Broadband, or SBB — and the state-controlled telecommunications company, Telekom Srbija.

Telekom Srbija recently made a move that many saw as an unfair effort to make SBB less attractive to consumers when it snagged from SBB the rights to broadcast English soccer by offering to pay 700 percent more for them.

Telekom Srbija’s offer, nearly $700 million for six seasons, is an astronomical amount for a country with only seven million people — and nearly four times what a media company in Russia, a far bigger market, has agreed to pay the Premier League each season for broadcast rights.

“It is very difficult to compete if you have a competitor that does not really care about profit,” SBB’s chief executive, Milija Zekovic, said in an interview.

Telekom Srbija declined to make its executives available for comment, but in public statements, the company has described its investments in English soccer and elsewhere as driven by commercial concerns, not politics.

“Their goal is to kill SBB,” Dragan Solak, the chairman of SBB’s parent company, United Group, said in an interview in London. “In the Balkans,” he added, “you do not want to be a bleeding shark.”

Eager to stay in the game, Mr. Solak announced this month that a private investment company he controls had bought Southampton FC, an English Premier League soccer team. Broadcast rights for the league will stay with his state-controlled rival, but part of the huge sum it agreed to pay for them will now pass to Mr. Solak.

Government loyalists run Serbia’s five main free-to-air television channels, including the supposedly neutral public broadcaster, RTS. The only television outlets in Serbia that give airtime to the opposition and avoid hagiographic coverage of Mr. Vucic are Mr. Solak’s cable news channel N1, which is affiliated with CNN, and his TV Nova.

Without them, Mr. Solak said, Serbia “will be heading into the dark ages like North Korea.”

Space for critical media has been shrinking across the region, with V-Dem Institute, the Swedish research group, now ranking Serbia, Poland and Hungary among its “top 10 autocratizing countries,” citing “assaults on the judiciary and restrictions on the media and civil society.” Freedom House now classifies Serbia as “partly free.”

In each country, security forces — the primary tools for muzzling critical voices during the communist era — have been replaced in this role by state-controlled and state-dependent companies that exert often irresistible pressure on the news media.

Poland’s governing party, Law and Justice, has turned the country’s public broadcaster, TVP, into a propaganda bullhorn, while a state-run oil company has taken over a string of regional newspapers, though some national print outlets still regularly assail the government.

In December, Law and Justice pushed through legislation that would have squeezed out the only independent television news channel, the American-owned TVN24, but the Polish president, worried about alienating Washington, vetoed the bill.

Hungary has gone further, gathering hundreds of news outlets into a holding company controlled by allies of Prime Minister Viktor Orban. Only one television station with national reach is critical of Mr. Orban and financially independent from his government.

Mr. Orban’s previously divided political rivals have formed a united front to fight elections in April but have been unsuccessful in shaking his stranglehold on the news media.

In Serbia, the media space for critical voices has shrunk so far, said Zoran Sekulic, the founder and editor of an independent news agency, that “the level of control, direct and indirect, is like in the 1990s” under Mr. Milosevic, whom Mr. Vucic served as information minister.

Journalists, Mr. Sekulic added, do not get killed anymore, but the system of control endures, only “upgraded and improved” to ensure fawning coverage without brute force.

When United Group started a relatively opposition-friendly newspaper last year, it could not find a printer in Serbia willing to touch it. The newspaper is printed in neighboring Croatia and sent into Serbia.

Dragan Djilas, the leader of Serbia’s main opposition party and formerly a media executive, complained that while Mr. Vucic could talk for hours without interruption on Serbia’s main television channels, opposition politicians appeared mostly only as targets for attack. “I am like an actor in a silent movie,” he said.

N1, the only channel that sometimes lets him talk, is widely watched in Belgrade, the capital, but is blocked in many towns and cities where mayors are members of Mr. Vucic’s party. Even in Belgrade, the cable company that hosts the channel has faced trouble entering new housing projects built by property developers with close ties to the government. A huge new housing area under construction for security officials near Belgrade, for example, has refused to install SBB’s cable, the company said.

Viewers of pro-government channels “live in a parallel universe,” said Zeljko Bodrozic, the president of the Independent Journalists Association of Serbia. Channels like TV Pink, the most popular national station, which features sexually explicit reality shows and long statements by Mr. Vucic, he said, “don’t just indoctrinate, but make people stupid.”

The European Union and the United States have repeatedly rebuked Mr. Vucic over the lack of media pluralism, but, eager to keep Serbia from embracing Russia or stoking unrest in neighboring Bosnia, have not pushed hard.

This has given Mr. Vucic a largely free hand to expand the media control that Rasa Nedeljkov, the program director in Belgrade for the Center for Research, Transparency and Accountability, described as “the skeleton of his whole system.” In some ways, he added, Serbia’s space for critical media is now smaller than it was under Mr. Milosevic, who “didn’t really care about having total control” and left various regional outlets untouched.

“Vucic is now learning from this mistake by Milosevic,” Mr. Nedeljkov said. Mr. Vucic and his allies, Mr. Nedeljkov added, “are not tolerating anything that is different.”

Once powerful independent voices have gradually been co-opted. The radio station B92, which regularly criticized Mr. Milosevic during the Balkan Wars of the 1990s, for example, is now owned by a supporter of Mr. Vucic and mostly parrots the government line.

Journalists and others who upset Mr. Vucic face venomous attacks by tabloid newspapers loyal to the authorities. Mr. Solak, the United Group chairman, for example, has been denounced as “Serbia’s biggest scammer,” a crook gnawing at the country “like scabies” and a traitor working for Serbia’s foreign foes.

Mr. Solak, who lives outside Serbia because of safety concerns, said he had become such a regular target for abuse that when he does not get attacked, “my friends call me and ask: What happened? Are you OK?”