The government confirmed Wednesday that it thwarted an attempt to overthrow Prime Minister Sadek Mahdi last week and arrested 25 civilians and retired soldiers.

Defense Minister Abdul-Maguid Khalil told reporters that the situation has been brought under control. He gave no other details.Khalil was confirming a report in the newspaper Al-Siyassa.

The independent paper reported that security men had crushed an attempted coup on Saturday and arrested 25 retired military officers and civilian officials from the former government of President Gaafar Nimeiri, who was ousted in an April 6, 1985, coup. It was the third newspaper report of an attempted coup in Sudan in the past two weeks.

After the Al-Siyassa report appeared Wednesday, about 300 demonstrators defied an emergency order and gathered in Khartoum's Liberty square to demand government approval of a tentative agreement to stop Sudan's civil war.

The demonstrators in Khartoum's Liberty Square also ignored a decision by rally organizers to call off the protest because Mahdi's government declared a special emergency in the Khartoum area.

Mohammed Osman Mirghani, spiritual leader of the Democratic Unionist Party and the negotiator of the peace agreement with rebel leader John Garang, reportedly urged that the peace march be postponed.

Garang, head of the Sudan People's Liberation Army, began his civil rebellion in early 1983 to press demands for what he considers fairer economic, political and administrative treatment for southern Sudan.

Mirghani told demonstration organizers that "new developments in the picture" made a postponement of the rally necessary "in the interests of peace," the independent newspaper Al-Ayam reported.

Riot police and plainclothes security men ringed the square as protestors chanted "No, no to war" and "Yes, yes to peace."