Police, using tear gas and water cannons, on Friday raided the headquarters of Turkey's largest-circulation newspaper, hours after a court placed it under the management of trustees. The move against the paper, which is linked to an opposition cleric, heightened concerns over deteriorating press freedoms in the country. Police dispersed protesters who had gathered outside of the opposition Zaman newspaper's Istanbul headquarters before breaking down a gate and entering the building to escort the court-appointed managers and evict newspaper workers. The court action against Zaman newspaper was brought by a public prosecutor and came amid an intensified government campaign against the moderate Islamic movement led by U.S.-based cleric Fethullah Gulen. It accuses the movement of attempting to bring down the government. The move, which also affects Zaman's sister newspaper, English-language Today's Zaman, and a news agency linked to the group, further reduces the pool of opposition television and newspapers in the country, which is dominated by pro-government television channels and newspapers. Zaman Editor-in-Chief Abdulhamit Bilici addressed his colleagues on the grounds of the newspaper before police had stormed the building. He called the court decision a "black day for democracy" in Turkey as journalists and other newspaper workers held up signs that read: "Don't touch my newspaper" and chanted "free press cannot be silenced!" The court decision sparked international outrage. "I see this as an extremely serious interference with media freedom which should have no place in a democratic society," said Nils Muiznieks, the Council of Europe Commissioner for Human Rights. "It is the latest in a string of unacceptable and undue restrictions of media freedom in Turkey." Reporters without Borders issued a strongly-worded statement, accusing President Recep Tayyip Erdogan of "moving from authoritarianism to all-out despotism." Gulen, who has lived in the United States since 1999, was once Erdogan's ally but the two have fallen out. The government accuses the Gulen movement of orchestrating corruption allegations in December 2013 against ministers and people close to Erdogan as a plot to overthrow it. Authorities have since branded the movement a terror organization, although it is not known to have carried out acts of violence.