ANKARA, Turkey (AP) — A court in Istanbul on Friday ordered that Turkey's largest-circulation newspaper, which is linked to an opposition cleric, be placed under the management of trustees — a move that heightens concerns over deteriorating press freedoms in Turkey.

The court action against Zaman newspaper comes as the government has intensified a 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 case was brought by a public prosecutor in Istanbul and means that the editorial board and management will be replaced by people named by the court.

The move further reduces the pool of opposition television and newspapers in the country, which is dominated by pro-government television channels and newspapers.

Gulen, who has lived in the United States since 1999, was once President Recep Tayyip Errdogan's ally but the two have fallen out.

The government accuses the Gulen movement of orchestrating corruption allegations in December 2013 into 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.

Gulen was placed on trial in absentia last year on charges of attempting to topple the government.

The government has cracked down on the movement since, purging civil servants suspected of ties to it, and businesses have been seized.

Earlier on Friday, police detained four senior officials of Boydak Holding company, which has ties to Gulen, over allegations that it provided financial support to the movement. The state-run Anadolu Agency says police in the central city of Kayseri detained Boydak Holding's chairman, chief executive officer and two board members.

In October, courts similarly placed four media organizations, owned by a company linked to Gulen under trusteeship, turning them into government mouthpieces.