The government is under mounting pressure from its people, political parties, army and Western aid donors to end a debilitating civil war and to begin fighting the famine and economic ruin it has caused.

Hesitant steps toward peace have been taken, mainly a provisional peace pact signed Nov. 16 by the rebels and the Democratic Unionist Party, the junior partner in Prime Minister Sadek el-Mahdi's governing coalition.But critics accuse el-Mahdi of dragging his feet in a ploy to ensure the Democratic Unionists cannot claim credit for restoring peace.

The provisional pact relaxed tensions to the point where the Red Cross and the United Nations were able to begin emergency airlifts Dec. 4 with guarantees from both sides that planes would not be fired on.

The planes are taking food and medicine to hundreds of thousands of victims of war-induced famine, blamed by U.N. officials for more than 500,000 deaths this year.

"Thousands of people died during the long months of negotiations," said Pierre Pont, Khartoum representative of the International Committee of the Red Cross. "I think both sides finally decided it was politically futile to continue to stop and impede the relief."

El-Mahdi has been getting a lot of political heat in the three weeks since John Garang, head of the rebel Sudan People's Liberation Army, signed the agreement that among other things calls for an immediate cease-fire.

The prime minister's Umma Party gave its support to the plan, but el-Mahdi has not presented it for Cabinet consideration. The third-largest party, the fundamentalist National Islamic Front, strongly objects to a key provision - freezing implementation of harsh punishments under Sudan's Islamic law and stopping discussions about a replacement penal code.

The Islamic party would be certain to leave the coalition if the Umma and Democratic Unionists joined with southern ministers to approve the plan. That most likely would bring down the government.

"Once again, (el-Mahdi) may be pursuing incompatible objectives," said one Western diplomat. "Peace is clearly a popular demand, and the (Islamic Front) is the only group critical of peace."

Garang began his civil rebellion in early 1983 to press demands for what he considers fairer economic, political and administrative treatment for southern Sudan.

Most people in the region are ethnic African Christians or animists, but the national government is dominated by Arab-descended Moslems. Garang has vowed not to stop fighting until Islamic law, decreed several months after he took up arms, is abrogated.

Diplomats say guns generally have fallen silent since the Nov. 16 pact, even though the agreement is not being implemented officially.

The prospect of peace is a hugely popular idea for the common Sudanese.

The government was spending $1 million a day before the de facto cease-fire took effect, a drain that ruined an already shaky economy. The Sudanese feel the drain daily in shortages of food and basic supplies, soaring prices and frequent shutdowns of public utilities.

Thousands turned out to greet the Democratic Unionists' spiritual leader, Mohammed Osman al-Mirghani, when he returned from Ethiopia after negotiating the agreement.

Last week, the Union of Sudanese Writers organized a "peace night" in Khartoum at which al-Mirghani and others spoke.

On a different level, the United States and other aid donors are applying political pressure on el-Mahdi's government.

At a meeting of Western donors last month to discuss financing a $407-million plan to help Sudan recover from major floods in August, the United States essentially told Khartoum to make peace first - and urged other donors to take the same position.