Turkish police have fired tear gas and rubber bullets at hundreds of protesters trying to resist a takeover of the country's biggest newspaper, seized by authorities in a crackdown on opposition media linked to a religious group whose leader lives in exile in the United States.

Police confronted around 500 protesters Saturday outside the Istanbul offices of Zaman, Turkey's largest-circulation daily.

Demonstrators chanted "free media cannot be silenced" as police closed in, spraying tear gas and firing rubber bullets at the demonstrators, many of whom were women.

The police action began Friday, when helmeted officers used powerful streams of water and clouds of tear gas to push demonstrators away from the newspaper's headquarters, then cut through a metal fence to occupy the building and install court-appointed trustees.

Zaman's chief editor, Abdulhamit Bilici, addressing his staff before police stormed in, called Friday "a black day for democracy" in Turkey. Media-rights groups have denounced the crackdown by President Recep Tayyip Erdogan's government

The crackdown, which also affected the English-language newspaper Today's Zaman, was the latest in a series of actions against Muslim cleric Fethullah Gulen, now a U.S. resident, whom the Ankara government accuses of treason.

Conspiracy accusations

Erdogan accuses Gulen of conspiring to overthrow the government by building a network of supporters in the judiciary, police and media. Gulen denies the charges. The two men were allies until police and prosecutors seen as sympathetic to Gulen opened a corruption probe into Erdogan's inner circle in 2013.

FILE - In this March 15, 2014, file photo, Turkish
FILE - Turkish Islamic preacher Fethullah Gulen.

Zaman is Turkey's biggest-selling newspaper with a circulation of 650,000, according to media-sector monitor MedyaTava website.

EU stance

"Zaman Media Group being silenced in Turkey. Crackdown on press freedom continues sadly," Kati Piri, the European Parliament's rapporteur on Turkey, said in a tweet.

The EU is accused of turning a blind eye to Turkey's human rights breaches, including the deaths of hundreds of civilians during security operations against Kurdish militants, because it needs Turkey's help curbing the flow of migrants.

The U.S.-based Committee to Protect Journalists spoke out against Friday's action. The head of the rights group, Joel Simon, said "Turkish authorities should be fulfilling their constitutional obligation to defend press freedom" rather than undermining opposition media with aggressive action.

CPJ has reported that Turkey is one of the top jailers of journalists in the world, with government officials taking advantage of laws that can be broadly interpreted to imprison journalists on suspicion of espionage, conspiracy, or defaming the government.

The crackdown on Zaman comes at an already worrying time for press freedom in Turkey.

Thousands of people gather in solidarity outside Z
Thousands of people gather in solidarity outside Zaman newspaper in Istanbul on March 4, 2016, after a local court ordered that Turkey's largest-circulation, opposition newspaper, which is linked to a U.S.-based Muslim cleric, be placed under the management of trustees — a move that heightens concerns over deteriorating press freedoms in Turkey.

Journalists facing potential life sentences

Two prominent journalists from the pro-opposition Cumhuriyet newspaper are facing potential life sentences on charges of endangering state security for publishing material that purports to show intelligence officials trucking arms to Syria.

Authorities have seized and shut down opposition media outlets associated with the Gulen movement before. The state deposit insurance fund said this past week an Islamic bank founded by Gulen followers might be liquidated within months.

The Zaman takeover came hours after police detained businessmen over allegations of financing what prosecutors described as a "Gulenist terror group," Anadolu said.

Memduh Boydak, chief executive of furniture-to-cables conglomerate Boydak Holding, as well as the group's chairman Haci Boydak and two board members, were taken into custody.

Nobody from the company, based in the central Turkish city of Kayseri, was available to comment.

Because of Turkey's geographical position as a bridge between East and West, and as a member of NATO, it has been a valuable ally to the United States and Europe on issues such as the civil war in Syria and the tide of refugees flowing west from Syria, Iraq and Afghanistan.

Critics of Turkey's government say the nation's value as an ally keeps Western nations from protesting too loudly about the Ankara's human rights record.

Some information for this report provided by Reuters.