Turkish police raided media outlets linked to U.S.-based Muslim cleric Fethullah Gulen today and detained 23 journalists and television producers.

The operation acted against what President Tayyip Erdogan claims is a network conspiring to topple him.

The raids on Zaman newspaper and Samanyolu television marked an escalation of Mr Erdogan's battle with former ally Mr Gulen.

Turkish police arrested 23 journalists and television producers in raids on media outlets linked to U.S.-based Muslim cleric Fethullah Gulen today

Staff and supporters of Zaman newspaper shout slogans as editor-in-chief Ekrem Dumanli, centre, is arrested by counter-terror police at the newspaper headquarters in Istanbul today

He has been in open conflict with Gulen since a graft investigation targeting Mr Erdogan's inner circle emerged a year ago.

'The free press cannot be silenced,' a crowd chanted outside Zaman's offices as its editor Ekrem Dumanli made a speech defiantly challenging police to detain him - as Hidayet Karaca, the chairman of Samanyolu TV, was arrested in Istanbul.

Just before his arrest, Mr Karaca told reporters: 'This is a shameful sight for Turkey.

'Sadly in 21st century Turkey, this is the treatment they dish out to a media group with tens of television and radio stations, internet media and magazines.'

Arrest warrants had reportedly been issued for 32 people.

A man holds a placard that reads 'a time for democracy' as people gather in support outside Zaman newspaper in Istanbul, Turkey

Supporters of cleric Fethullah Gulen read the Koran and newspapers as they wait outside a courthouse after Turkish police began an operation targeting the media

State broadcaster TRT Haber said 23 people were detained in raids across the country, including two former police chiefs.

As well as Mr Karaca, a television producer, a director and scriptwriters were held.

Mr Erdogan introduced many democratic reforms in his first years in power and curbed army involvement in politics after his AK Party was elected in 2002.

NATO allies often cited Turkey, a candidate for the EU, as an example of a successful Muslim democracy.

But more recently critics have accused the President of intolerance of dissent and, increasingly, a divisive reversion to Islamist roots.

English-language Today's Zaman editor Bulent Kenes told Reuters police had shown them documentation which referred to a charge of 'forming a gang to try and seize state sovereignty'.

Zaman editor-in-chief Ekrem Dumanli is escorted by plainclothes police officers and cheered on by his colleagues as he leaves Zaman's headquarters

Mr Dumanli kisses a Turkish flag as supporters of the Fethullah Gulen movement surround him

Crowds chanted 'The free press cannot be silenced,' outside Zaman's offices as its editor Ekrem Dumanli, right, was detained

Government ministers declined to make specific comments on the raids, but Health Minister Mehmet Muezzinoglu, according to state media, said: 'Anyone who does wrong pays the price'.

Main opposition CHP leader Kemal Kilicdaroglu said: 'This is a coup government. A coup is being carried out against democracy'.

Mr Erdogan has accused Mr Gulen of establishing a 'parallel structure' within the state through his supporters in the judiciary, police and other state institutions, as well as wielding influence through the media.

The cleric denies the accusation of seeking to overthrow Mr Erdogan's government.

Mr Erdogan drew on Mr Gulen's influence on the police and judiciary in the first years of his government in taming an army that had toppled four administrations since 1960, including Turkey's first Islamist-led cabinet.

That relationship has dramatically soured.

Turkish police launched a sweeping operation to arrest supporters of President Tayyip Erdogan's rival, US-exiled imam Fethullah Gulen

Mr Dumanli, left, made a speech defiantly challenging police to detain him, and right, film director Engin Koc was also arrested

Plain-clothed Turkish policemen arrest TV producer Salih Asan as part of an operation to simultaneously detain broadcasters and journalists

Mr Gulen denies the accusation of seeking to overthrow Mr Erdogan's government. Pictured, TV producer Salih Asan is arrested

Mr Erdogan, who consolidated his power further in moving from the prime minister's office to the presidency in August, said on Friday he would pursue Mr Gulen's supporters into their 'lairs'.

He has described them in the past as terrorists and traitors.

The graft investigation, which became public with police raids on December 17 last year, led to the resignation of three ministers and prompted Mr Erdogan to purge the state apparatus.

He reassigned thousands of police and hundreds of judges and prosecutors and has also pushed through legislation increasing government control of the judiciary - most recently a law restructuring two top courts.

Meanwhile, prosecutors have dropped the corruption cases.

Today's police raids had been expected for several days after a widely-followed Twitter account, which has previously given advance warning of police operations, said police were set to detain around 400 people, including around 150 journalists regarded as Mr Gulen supporters.

Health Minister Mehmet Muezzinoglu said: 'Anyone who does wrong pays the price'. Pictured, Ekrem Dumanli