Scrambling to avoid a power vacuum in the wake of Gen. Sani Abacha's unex

pected death, the ruling military moved quickly Tuesday to appoint another general as Nigeria's new head of state.Abdulsalam Abubakar, wearing a beret and army green, was sworn into office during a pre-dawn ceremony, becoming the ninth military leader in oil-rich Nigeria, Africa's most populous nation.

Although the immediate question of succession was answered, many Nigerians were waiting to see if Abubakar would push forward with some form of political transition to democratic rule this year.

Abacha in the final months of his life appeared again to be moving away from his pledge to hand power over to an elected civilian government.

Abacha's five years of iron-fisted rule came to an abrupt end Monday when a fatal heart attack cut him down in his sleep. He was 54.

Abacha leaves behind an impoverished country, despite its vast oil reserves. Endemic corruption, intolerance to dissent and a dismal human rights record are the hallmarks of Abacha's leadership.

Although the sixth largest oil exporter, Nigeria must import refined fuel and faces chronic gasoline shortages.

"I appeal to all Nigerians to put all hands on deck to move our nation forward," Abubakar said in a statement shortly after his appointment, which came less than 12 hours after Abacha's death was announced.

Abubakar declared seven days of mourning for Abacha and ordered flags be flown at half staff.

Abacha came to power in a coup after canceling presidential elections in 1993. He never indicated who would take his place as leader of Nigeria's 115 million people.

Many in the commercial capital, Lagos, celebrated Abacha's death, saying their country may now have a chance for democracy.

"You might think it is strange for people to rejoice at the death of someone," said Marcus Okoye, a executive with a local oil company. "This is not just another death - many in Nigeria think it's the death of dictatorship."

In keeping with Muslim practice, Abacha was buried in Kano before sundown Monday.

Abubakar, 55, was born in the northern Nigerian town of Minna and later attended the Kaduna Technical Institute in 1963 before enlisting in the air force.

A career serviceman, he transferred to the army in 1975 and received military training in the United States. In 1981 he served with Nigerian troops assigned to a United Nations peacekeeping force in Lebanon. He was appointed chief of defense staff in 1993 by Abacha.