Nigeria's new military government has promised to release all political prisoners, including Moshood Abiola, the nation's leading opposition figure, U.N. Secretary-General Kofi Annan said Thursday.

Abiola, 60, was the apparent winner of Nigeria's 1993 presidential election - a vote that was annulled by the military regime.Several months later, the late Gen. Sani Abacha came to power in a coup, jailing Abiola in 1994 when the opposition leader declared himself president.

"I'm leaving Nigeria with the stage set for the release of all political detainees," Annan said Thursday.

Annan confirmed that he met with Abiola on Tuesday and said the wealthy Nigerian businessman was alert and in good health.

Annan said Abiola had decided to relinquish his claim to the presidency and cooperate with the new military ruler, Gen. Abdulsalam Abubakar, to prepare the West African nation - Africa's most populous - for a peaceful transition to democracy.