Police in Istanbul carried out a dawn raid Wednesday, using tear gas to enter the headquarters of a media company linked to a U.S.-based government critic. The raid enforced a Monday court order to seize the business just days before a national election.

A prosecutor has ordered Koza-Ipek Holding placed under the management of a trustee while its ties to the movement led by Pennsylvania resident and moderate Islamic cleric Fethullah Gulen are investigated.

The government has accused Gulen’s movement of trying to destabilize the state and prosecutors have labeled it a terrorist organization.

The move was part of a broad crackdown on Gulen’s supporters that has been underway since December 2013 when prosecutors launched a corruption investigation of government ministers and people close to President Recep Tayyip Erdogan. Erdogan alleges that the probes were part of an attempted coup.

Hundreds of police and judiciary officials suspected of ties to Gulen's movement have been dismissed. In May, Turkey's banking regulator seized a bank associated with the movement.

Opposition parties denounced the seizure as an unlawful attempt by Erdogan to silence critical media ahead of Turkey's Sunday's election. Koza-Ipek owns opposition television stations Bugun TV and Kanal Turk, the Bugun and Millet newspapers and other business interests.

Police scuffled with hundreds of Koza-Ipek employees, supporters and opposition legislators who gathered in a show of support, before breaking down iron gates and escorting the newly appointed trustees into the building. The commotion was broadcast live by Bugun TV and Kanal Turk.

Bugun TV editor Tarik Toros was seen arguing with the trustee manager who entered the station's control room and apparently put an end to the live broadcast.

Protesters chanted "free media cannot be silenced." Some demonstrators were seen being thrown to the ground before being detained. Others used umbrellas to shield their faces from police pepper spray.

"We are faced with an unacceptable incident," said Haluk Koc, a deputy chairman of main opposition the Republican People's Party. "(Erdogan) sees himself as above the law and is busy massacring laws as he sees fit."

There was no immediate government comment.

Akin Ipek, Koza-Ipek's executive board chairman, has denied allegations of financial wrongdoing by the company.

"The group has been audited by independent companies since it was founded. They are lying and trying to slur us," Ipek said in a telephone interview with Bugun TV as police attempted to enter the building.

Journalism groups also condemned the seizure.

The government "is trying to silence every single dissenter days ahead of the election," the Ankara-based Contemporary Journalists' Association said in a statement.

The seizure comes amid more widespread pressure on critical media in Turkey that international watchdogs have called a crisis for the free press. Last month, the headquarters of secular-leaning Turkish daily Hurriyet was vandalized by a mob following verbal attacks on the newspaper by Erdogan.

The Associated press contributed to this report.