ANKARA, Turkey — Turkey's military chief held urgent meetings today with the prime minister and president following the detention of three retired generals and nine active duty officers in a probe into an alleged coup plot.

A military statement said Gen. Ilker Basbug had expressed his views on the detentions. The army, which once called the shots in the country, is widely believed to be angry about the detentions, which have stunned the nation.

Fears of political instability caused the stock market to plummet by 5 percent today.

Eighty-six people — including 16 former army officers, several journalists, a former university dean and a lawyer — already are on trial in the case. They have pleaded innocent and accuse Prime Minister Recep Tayyip Erdogan's government of attempting to silence secular critics.

The defendants are accused of being a member of a "terrorist organization" and of trying to destabilize Turkey with a string of attacks before a coup, designed to bring down the Islamic-rooted government, that was never carried out.