The government appointed an overseer to the last big news channel critical of President Recep Tayyip Erdogan. The authorities have now replaced the leadership at five major news outlets.

The police swept into the headquarters of Turkey’s most widely watched pro-opposition news channel before dawn on Wednesday, and when the time came for its morning news show, viewers instead saw only recycled shows from its archives.

A court had appointed an administrator to take over the channel, Halk TV, bringing under government control the last major broadcaster in Turkey that is critical of President Recep Tayyip Erdogan.

Halk TV is the fifth major pro-opposition news outlet to have its leadership replaced by a government overseer, or “trustee,” elevating concerns that Turkey’s already constrained media environment is being further constricted in the run-up to elections widely expected next year.

Turkish courts have also imposed trustees on companies and municipalities associated with Mr. Erdogan’s political foes, who accuse his government of using the law to weaken its political opposition.

“A dawn raid on a television channel, appointing a trustee — only dictators would do such a thing,” Ozgur Ozel, the head of Turkey’s largest opposition party, wrote on social media.

He accused the government of appointing overseers to “trample the people’s will” amid widespread concern over the rising cost of living.

The Istanbul Chief Prosecutor’s Office said the raid on Halk TV was part of an investigation into the channel’s chairman, Cafer Mahiroglu, on suspicion of bribery, bid rigging and money laundering. It ordered the detention of him and 16 other people, 11 of whom are already in custody.

Mr. Mahiroglu, who is outside Turkey, said seven of those detained were his relatives. He has denied all charges.

Halk TV provided continuous coverage of local and international news but with a clear orientation toward the political opposition, whose speeches, rallies and meetings other channels often ignore.

During the last two years, the government has launched a vast series of legal moves against Mr. Erdogan’s opponents. Scores of opposition party figures, including elected mayors, have been arrested, mostly on corruption-related charges.

The crackdown has altered Turkey’s political map. A court ruling caused the country’s largest opposition party to split in two, dividing Mr. Erdogan’s foes. Some opposition mayors have been removed from office and replaced by members of Mr. Erdogan’s governing Justice and Development Party.

Last week, the mayor of Izmir, Turkey’s third largest city and a historic opposition bastion, shocked his colleagues by defecting to Mr. Erdogan’s party.

The government says its legal system is free from political interference. Mr. Erdogan has characterized the opposition as deeply corrupt, comparing what he calls its illegal it schemes to “the arms of an octopus.”In an interview, Bahadır Ozgur, an investigative columnist and correspondent at Halk TV, said that riot police had blocked off the street to the headquarters early Wednesday while other officers searched its offices.

No journalists remain in the channel’s control room, he said, and its social media accounts are all controlled by the trustee.

He said the seizure of the channel was part of a broad effort to “incapacitate all of the opposition’s means” since it won local elections in many of Turkey’s largest cities in 2024.

“It was Halk TV’s turn as the most effective media outlet of the opposition,” Mr. Ozgur said.

Mr. Mahiroglu, the chairman of the channel, said in a video posted on social media that seven members of his family had been arrested, including his 70-year-old brother.

“Today is a dark day for Turkey,” he said. “People’s right to receive news is being prevented, with political aims.”The seizure of Halk TV came hours before a top opposition politician, Ekrem Imamoglu, was expected to present his defense in court against charges that he ran a criminal organization inside Istanbul’s City Hall while serving as mayor between 2019 and 2025.

The channel was expected to cover the defense, while Turkey’s government-aligned channels have said little about the trial.

Mr. Imamoglu, who was arrested last year after announcing that he planned to challenge Mr. Erdogan in Turkey’s next presidential election, has dismissed the charges against him as politically motivated. He recently intended to publish a book to make his case directly to voters, but a court banned it just days before it was to hit the shelves.

Turkey rated 163rd out of 180 countries on Reporters Without Borders’ 2026 World Press Freedom Index.

“Authoritarianism is gaining ground in Turkey and media pluralism is being called into question,” the organization wrote. “All possible means are used to undermine critics.”Mr. Erdogan’s current presidential term ends in 2028, but he could seek another five-year mandate if Parliament calls for early elections, which most analysts expect to happen sometime next year.

Ben Hubbard is the Istanbul bureau chief for The Times, covering Turkey and the surrounding region. Şafak Timur covers Turkey and is based in Istanbul.