An 11-member military committee has assumed power in the People's Republic of the Congo following the assassination yesterday of president Marien Ngouabi, the Congo radio reported today.

Radio Ecazzaville, monitored here, said Ngouabi was facally shot by a Capt. Earthelemy Kikadidi, who led an "imperialist suicide commando" squad in attacking the 39-year-old president at army headquarters.

The radio said the attackers escaped and it appealed to the whole nation to find them. It said Ngouabi, shot in the jaw, died "with a gun in his hand."

The four-man commando group that assassinated Congolese President Ngouabi managed to approach his residence by telling guards they had an urgent messgae for him, according to the Congolese radio.

The team, led by Kikadidi, passed successive checkpoints in their car and then seized control of the president's quarters where he was lunching, the radio said.

The president's son and bodyguards fred on the commandos but Ngouabi was hit by several bullets in the head, the radio said. Two bodyguards were also killed, it added.

Kikadidi, described as a close associate of former President Alphonse Massamba-Debat, was being sought in a countrywide manhunt, the radio said.

A communique issued by the ruling party said: "Imperialism, with its back to the wall, has with one last bound managed to take the life of the dynamic leader of the Congolese revolution."

The assassination followed recent charges by officials of the impoverisited West African country that imperialist saboteurs were trying "to bring about changes in orientation" among leftist countries on the continent. The Congo has especially close ties to the government of Angola and has had hostile relations with neighboring pre-Western Zaire.

In a statement March 1, Pierre Tryster Tehicaya, a high Congolese official, referred to a "difficult and dangerous" internal situation that he said, was brought about by a "vast imperialist sabotage plan."

Angola's national radio charged that the slaying was "part of the general imperialist plan to demoralize progressive people." It said the killing occurred "at a moment when there is a popular uprising in Zaire against the regime of President Mobutu Sese Sein" and noted that the Congo had always aided in the fight for the liberation of southern Africa.

Radio Brazzaville said the ruling committee would "assure the safety of the people and the revolution, manage affairs of state and prepare for the state funeral" of Ngouabi.

The committee announced a dust-to-dawn curfew nationwide, closed the borders until further notice, banned meetings of more than five people and decreed a month-long period of mourning.

Ngouabi seized power in a military coup Aug. 3, 1968, and was formally named chief of state in January 1969. The following December he proclaimed a "people's republic" and steered the country on a leftist course.

The Soviet news agency, Tass, referred to Ngouabi as "a tireless fighter for freedom and independence of the African peoples, who consistently came out against imperialism, colonialism, neocolonialism and racism."

Ngouabi was the third regularly installed chief of state since the nation of 1.3 million people gained independence from France in 1960. He appeared on the national political stage in 1966 when some army members protested his reduction in grade from captain to private first class.

During the revolt, the army chief of staff was arrested and the officers of the only authorized party, were sacked. Two years later President Alphonse Massamba-Debat was forced to resign and the National Council of the Revolution, headed by Ngouabi, took power.

Caryle Murphy Washington Post Staf writer, added in Washington:

Brazzaville became the home base of Agostinho Neto's Popular Movement for the Liberation of Angola after it was thrown out of Kinshasa by Zaire President Mobutu Sese Seko in the late 1960s.

The Angolans, especially those in Neto's now-ruling movement, thus have strong personal as well as ideological ties reaching back to the Cono and its slain leader.

When the Angolan civil war ended in Neto's victory, Ngouabi mediated to reconcile Mobutu and Neto in Brazzaville in February 1976. It was Neto's first postwar trip and was meant to symbolise his esteem for the Congo.

During the war, the Popular Movement had a few guerrilla bases in southern Congo, from which it launched attacks on the Cabinda enclave. Soviet transports that brought Cuban troops and Soviet arms to Neto refueled in Brazzaville.

Even while the Portuguese still ruled Angola - but after the Popular Movement was fighting there - arms were being shipped clandestinely from Pointe Noire, the Congo's main port, by boat to Luanda.