Aden radio made the first official mention yesterday of casualties in the fighting which led to the overthrow and execution of South Yemeni President Salim Robaya Ali last Monday.

The radio said that the central committee of the ruling National Front observed one minute's silence "in mourning for the martyrs who fell while foiling the attempted coup" by Robaya Ali. The presidential palace in Aden was reported to have been bombed and shelled by elements seeking a stronger alliance of the Marxist state with the Soviet Union.

The radio said the committee also discussed the aftermath of what it called the bloody attempt by Robaya Ali to impose his power on the country's collective leadership.

It said that the National Front's secretary general, Abdul Fattah Ismail, had presided over the meeting and would announce important decisions soon. Ismail and Prime Minister Ali Nasser Mohammed now make up the country's presidential council.

In Beirut, a Lebanese leftist newspaper said Cuban advisers and pilots tipped the balance in favor of the pro-Moscow forces in South Yemen.

The pro-Iraqui newspaper Al Liwa said 600 Cuban advisers "have been in complete control of military matters in South Yemen for the past two months."

Quoting a "diplomatic report" from Aden, the newspaper said the Cuban forces "spearheaded the attack against Robaya Ali at the presidential palace and it was Cuban pilots who flew the Mig fighters which pounded the palace where Robaya Ali and his supporters were entrenched."

U.S. analysts said they had no information of any Cuban role in the Aden clash. They said there are about 1,000 Soviet, East German and Cubans in South Yemen, half working as military advisers and half as economic advisers. East Germans are primarily involved in internal security, Cubans with the militia and Soviets with the armed forces, they said.

Robaya Ali's ouster came three days after the assassination of the president of neighboring North Yemen by a bomb carrier in the briefcase of a South Yemen envoy.

In Cairo, the semi-official Egyptian newspaper Al Ahram reported that Robaya Ali did not engineer Saturday's assassination of North Yemen President Ahmed Hussein Ghashmi, but in fact tried to save his life.

Al Ahram said that when Robaya Ali learned the envoy's briefcase had been replaced by a booby-trapped one, he tried to warn the Ghashmi by telephone, but the call did not get through in time.

Al Ahram appeared to blame the pro-Moscow wing of the Front for killing both Ghashmi and Robaya Ali.

The Iraqi news service reported from the North Yemeni capital of Sanaa that U.S. special envoy Joseph Twinam delivered a message from President Carter to North Yemen's new provisional head of state, Abdel Karim Arshi.