The former commander of Turkey's paramilitary forces was arrested
A senior Turkish general has called for calm after a wave of arrests during a police investigation into a suspected anti-government plot.
Two retired generals were among 20 people detained in arrests targeting a shadowy ultra-nationalist group.
Turkey's Prime Minister Recep Tayyip Erdogan denied the arrests were politically-motivated.
The arrests came as the country's chief prosecutor appeared in court calling for the ruling party to be disbanded.
Simultaneous raids took place in Ankara, Istanbul and three other cities targeting alleged members of the Ergenekon group on Tuesday.
Secularists have staged huge anti-AKP rallies
At least 20 people were arrested, including figures from the military and journalism.
Former Gen Sener Eruygur - involved in organising anti-government rallies last year - and ex Gen Hursit Tolon were the highest ranking officials arrested so far.
They are among a list of dozens of people implicated in an alleged plot to topple the government after explosives were found in Istanbul last year.
"Turkey is passing through difficult days. We all have to be acting with more common sense, more carefully and more responsibly," said Gen Ilker Basbug, the second most powerful general in the Turkish armed forces.
The BBC's Sarah Rainsford, in Istanbul, says the arrests have provoked accusations of a political witch-hunt from the opposition which says the government is using the investigation to exact revenge.
The arrests came as the country's chief prosecutor appeared in court accusing the ruling Justice and Development Party, the AKP, of being anti-constitutional and trying to impose Sharia law on the secular state.
Founded by Mr Erdogan, the AKP won a landslide victory in the last election.
But Prosecutor Abdurrahman Yalcinkaya argues that the party has become the focal point of anti-secular activities in Turkey.
He is calling for the party to be closed down and the prime minister, president and 69 other party members to be banned from politics.
The AKP, formed after a previous pro-Islamic party was banned, has condemned the case as an assault on democracy. It is expected to present its defence on Thursday.
Its founders have since steered a moderate path, pursuing democratic reforms and directing Turkey towards the EU, our correspondent says.