Turkish media say authorities have arrested at least seven people in connection with an alleged plot to overthrow the Islamic-leaning government.
Saturday's reports say the chairman of the Ankara chamber of commerce, Sinan Aygun, was among those arrested. Prosecutors also asked the court to arrest two former generals.
Authorities say they uncovered the coup plot during raids on suspected members of a hard-line secularist network known as Ergenekon. They say the suspects planned to stage illegal protests across Turkey on July 7, to carry out assassinations and to trigger battles with security forces.
It is not clear what charges have been brought against the suspects.
Turkish police detained 21 suspected members of the Ergenekon network Tuesday. Opposition groups called the arrests part of a government campaign to intimidate critics. A ruling party official said the government is acting according to its obligations.
Eleven of the detainees have been released. But some of them, including the Ankara representative of a secularist newspaper, have been barred from leaving the country while the case continues.
Some information for this report was provided by AFP and Reuters.