Washington — A week after the death of Nigerian military ruler Sani Abacha, his successor today announced the release of former head-of-state Olusegun Obasanjo and other prominent leaders who had been jailed for opposing Abacha's authority.

The actions led to widespread speculation that the authorities also plan to free Moshood K. O. Abiola, the businessman who is believed to have won the aborted 1993 presidential elections.

The releases followed by one day a telephone call from President Clinton to the newly installed Nigerian head-of-state, Gen. Abdulsalam Abubakar. According to a White House statement, the President conveyed U.S. hopes for a rapid transition to civilian democratic government in Nigeria, by October 1, as reiterated by General Abubakar in his address to the Nigerian people last week.

Obasanjo, who is 62, was serving a 15-year sentence for allegedly taking part in a 1995 coup plot. The only Nigerian military leader to have presided over a transition to an elected civilian government since independence in 1960, Obasanjo led the country from 1976 to 1979. He has been ordered confined to his farm outside Lagos.

Others whose release was announced include newspaper editor Christiana Anyanwu, Bola Ige, who is a former state governor, human rights activist Beko Ransome-Kuti, trade union leaders Frank Kokori and Milton Dabibi, Islamic leader Ibrahim Dasuki, and Olabintan Durojaiye and Uwen Udoh, both pro-democracy advocates.

In Washington, a White House spokesman, P.J. Crowley said: "We hope this important step will lead to further releases and will help all Nigerians come together to work to support a credible and open transition to civilian democratic government."