A Turkish military commander has called for calm after two prominent retired generals were detained in a widening police investigation into a suspected coup plot against the government.

General Ilker Basbug said: "Turkey is passing through difficult days. We all have to be acting with more common sense, more carefully and more responsibly."

Police have detained 21 people as part of a year-long investigation into Ergenekon, an ultra-nationalist secularist group suspected of planning bombings to trigger a military takeover.

The detentions of known critics of the government come as the ruling AK party fights for its survival in court.

The chief prosecutor of the court of appeals is seeking the closure of the party on charges that it has violated the principle of secularism enshrined in the constitution.

The party denies the charges.

Public shock

NTV, a Turkish broadcaster, reported on Wednesday that Turhan Colakkadi, the Istanbul deputy chief prosecutor, said an indictment against Ergenekon had been completed and its members would be tried for terrorism.

The detentions of General Hursit Tolon, the retired first army chief and General
Sener Eruygur, a retired gendarmerie forces commander, inside their army residences on Tuesday sent shockwaves across a country where the military is held in high respect.

The army said the raids were within the law.

Other prominent figures detained included Mustafa Balbay, a journalist from the secular Cumhuriyet newspaper, some politicians and the chairman of the Ankara chamber of commerce, all vocal critics of the ruling AK party.

"The raids yesterday were reminiscent of previous coups and are not acceptable," Rifat Hisarciklioglu, the chairman of the Turkish union of chambers and commodities exchanges, said in a speech at the Ankara chamber of commerce on Wednesday.

Some newspapers said that the fresh detentions had revived debate in Turkey over whether the allegations of a coup against the AK party were credible or were being used to suppress government opponents.