Turkish police have used tear gas, water cannon and plastic bullets to break up a protest by hundreds of people against the imprisonment of a group of journalists from secularist opposition newspaper Cumhuriye.

Riot police rapidly moved in as protestors demonstrated outside a mosque in Istanbul, shouting slogans denouncing the “fascist” state and vowing “we will not be silent”, hours after nine journalists were formally arrested pending trial by an Istanbul court.

The crowds were dispersed as officers sprayed torrents of freezing water from trucks, as well as using tear gas and firing plastic bullets, according to AFP.

The journalists, who include some of the most prominent names in Turkish journalism, were arrested in raids on Monday and will now be held behind bars ahead of a trial, as part of an intensifying crackdown on dissent by President Recep Tayyip Erdogan.

Following their arrests Turkish courts ordered a media blackout, prohibiting the press from reporting on the detention of Cumhuriyet journalists.

The arrests are the latest in a huge crackdown following a failed coup attempt to oust President Erdogan in July. Since the coup, more than 100 media outlets have been shut and dozens of journalists detained.

Prosecutors said staff at the paper, one of the few still critical of President Erdogan, were suspected of crimes committed on behalf of Kurdish militants and US-based cleric Fethullah Gulen, who is accused of instigating the coup attempt by the government. He denies any involvement.

Earlier this year the former editor-in-chief of Cumhuriyet, Can Dundar, was given a five years and 10-month jail sentence for revealing state secrets in a front-page story.

Protesters hold copies of the latest edition of the Turkish daily newspaper Cumhuriyet after nine of its journalists were placed under arrest (Yasin Akgul/Getty)

Following his detention, Mr Dundar wrote on Twitter: “Our ‘crime’ is our writing, our headlines, our news. We will write again. We will write even more...”

It comes days after two leaders of the Peoples’ Democratic Party (HDP), along with up to 11 other MPs from the group, whose support base is largely made up of Kurds from the region.

Selahattin Demirtas and Figen Yuksekdag were detained at their homes in Ankara as part of a counter-terrorism investigation, security sources told Turkish media.

After his arrest, Mr Demirtas said in a written statement read by his lawyer that he was the victim of a “civilian coup by the government and the palace”.

On Saturday, authorities appointed a new mayor to Sirnak municipality, part of a campaign over recent weeks of replacing pro-Kurdish officials in the mostly Kurdish southeast.

A bomb in Sirnak province on Saturday killed two children and wounded four, an attack that the local governor's office blamed on the outlawed Kurdistan Workers Party (PKK).

The recent spate of arrests of dissenters has sparked immediate alarm among Turkey's Western allies.

EU foreign policy chief Federica Mogherini said she was “extremely worried” over the detentions, while US State Department spokesman John Kirby said there was a “worrisome trend” of limiting freedom of expression in Turkey.

The Turkish authorities sparked further controversy on Friday by slapping restrictions on social media and messaging services like WhatsApp.

In pictures: Turkey coup attempt Show all 17 1 /17 In pictures: Turkey coup attempt In pictures: Turkey coup attempt Turkish President Erdogan attends the funeral service for victims of the thwarted coup in Istanbul at Fatih mosque on July 17, 2016 in Istanbul, Turkey Burak Kara/Getty Images In pictures: Turkey coup attempt Soldiers involved in the coup attempt surrender on Bosphorus bridge with their hands raised in Istanbul on 16 July, 2016 Gokhan Tan/Getty In pictures: Turkey coup attempt A civilian beats a soldier after troops involved in the coup surrendered on the Bosphorus Bridge in Istanbul, Turkey, 16 July, 2016 REUTERS/Murad Sezer In pictures: Turkey coup attempt Surrendered Turkish soldiers who were involved in the coup are beaten by a civilian Reuters In pictures: Turkey coup attempt Soliders involved in the coup attempt surrender on Bosphorus bridge Getty In pictures: Turkey coup attempt Supporters of Turkish President Recep Tayyip Erdogan wave flags as they capture a Turkish Army vehicle Getty In pictures: Turkey coup attempt People pose near a tank after troops involved in the coup surrendered on the Bosphorus Bridge in Istanbul, Turkey, 16 July, 2016 Reuters In pictures: Turkey coup attempt Turkish soldiers block Istanbul's Bosphorus Brigde Getty In pictures: Turkey coup attempt A Turkish military stands guard near the Taksim Square in Istanbul Reuters In pictures: Turkey coup attempt Pierre Crom/Twitter In pictures: Turkey coup attempt Turkish soldiers secure the area as supporters of Recep Tayyip Erdogan protest in Istanbul's Taksim square AP In pictures: Turkey coup attempt People demonstrate in front of the Republic Monument at the Taksim Square in Istanbul Murad Sezer/Reuters In pictures: Turkey coup attempt Turkish soldiers detain police officers during a security shutdown of the Bosphorus Bridge Reuters In pictures: Turkey coup attempt Turkish Army armoured personnel carriers in the main streets of Istanbul Getty In pictures: Turkey coup attempt Chaos reigned in Istanbul as tanks drove through the streets EPA/TOLGA BOZOGLU In pictures: Turkey coup attempt Turkish President Tayyip Erdogan speaks to media in the resort town of Marmaris Reuters In pictures: Turkey coup attempt Supporters of President Erdogan celebrate in Ankara following the suppression of the attempted coup Reuters

Users were still encountering problems loading social media on Saturday and had trouble using Virtual Private Network (VPN) connections, which people often use to circumvent such restrictions.

Turkey remains under a state of emergency that was imposed after the failed coup in July, which allows President Erdogan and his government to bypass parliament when drafting new laws and to restrict or suspend rights and freedoms.