HARARE, ZIMBABWE, DEC. 31 -- With tribal drummers and dancers performing and Chinese-built MiG warplanes screaming overhead, Robert Mugabe was sworn in today as the nation's first executive president.

Mugabe, 63, received the symbolic chain of office from the outgoing head of state, the Rev. Canaan Banana, before a cheering crowd of about 60,000 people, including six African heads of state, at the national sports stadium.

Mugabe, formerly prime minister and minister of defense, is armed with sweeping constitutional powers to carry out his aim of transforming Zimbabwe from a western-style democracy into a one-party socialist state. As president, he will combine the offices of head of state, chief of government and commander of the armed forces.

On Dec. 23, he and longtime political rival Joshua Nkomo agreed to merge their two parties as a first step in the transformation.

Mugabe said he would be guided by his ruling Zimbabwe African National Union (Patriotic Front) Party. "Executive power can never rightly be a one-man show," he declared. "Ours is and must always remain a people-oriented revolutionary path guided by socialist principles."

The former schoolteacher was embraced by heads of state from Botswana, Ethiopia, Mozambique, Tanzania, Uganda and Zambia. Clutching a Bible, Mugabe pledged allegiance to the nation and its 8.2 million people as he was formally sworn in by Chief Justice Enock Dumbutshena.

While hundreds of whites joined blacks in the stadium, Ian Smith was notably absent. Smith was the last leader of white Rhodesia, and held Mugabe as a political prisoner for a decade without charge or trial. Smith was not available at his Harare home.

Mugabe paid special tribute to Banana, a Methodist minister who plans to return to the clergy after serving as ceremonial head of state since independence. Banana was praised for helping to organize the talks between Mugabe and Nkomo that led to their unity agreement.

The accord is expected to ease hostilities between Mugabe's party and the Zimbabwe African People's Union of Nkomo. The ethnic divisions have spurred violence between the Army and Nkomo's followers in southern Zimbabwe since 1982. In 1980, Mugabe led the former British colony of Rhodesia to independence as black-governed Zimbabwe.