The alleged plot was first reported in June by Taraf, a Turkish newspaper that printed a photocopy of an alleged plan to blemish the government's reputation by portraying it as corrupt.

The military initially denied such a plan and military and civilian probes were inconclusive because the original document was not available. But a military officer allegedly provided prosecutors with the original document, reviving investigations, Turkish media reported last month.

Addressing ruling party lawmakers in parliament, Prime Minister Recep Tayyip Erdogan called on the military to help prosecutors track down suspects in the armed forces.

"If there are suspects there, they must be exposed and they must be handed over to justice," Erdogan said. "Those in the leadership position should not act conservatively and should hand them over to justice with ease."

Prosecutors last week questioned six officers over allegations that army personnel tried to destroy evidence.

In June, Gen. Ilker Basbug, the military chief, denied that such a plan was concocted at military headquarters and vowed to purge any soldiers who failed to respect democracy.

The military, which has deposed four governments since the 1960s, has sparred with Erdogan's government, which it suspects of moving Turkey away from its secular traditions. The generals have seen their powers wane as Turkey strengthens its civilian rule.

The latest controversy comes amid a trial of civilians, retired generals and active-duty officers accused of trying to topple the government.