Angola's leftist government and guerrillas have reached a peace accord in one of Africa's longest and bloodiest civil wars, with the United States and Soviet Union agreeing to stop arming the rivals.

Negotiators clasped hands at this coastal resort Wednesday to seal provisional accords that call for a cease-fire at the end of May and Angola's first free elections in the fall of 1992.The war has cost an estimated 300,000 lives since it began in 1975, the year Angola gained independence from Portugal.

"We have succeeded in crossing the Rubicon in this complex process, in this monumental work for lasting peace, democracy and dignity for our people in Angola," said guerrilla leader Jeremias Chitunda.

He is vice president of the National Union for the Total Independence of Angola, known as UNITA, supported by the United States in its fight against the Soviet-backed government.