ABUJA Nigerian President Umaru Yar'Adua has died at age 58 after a long illness, presidential aides said.
State television said on Thursday that acting President Goodluck Jonathan had been informed of Yar'Adua's death and the government would make a statement shortly.
Yar'Adua had been absent from the political scene in Africa's most populous nation since November, when he left for medical treatment for a heart condition in Saudi Arabia. He returned to Nigeria in February but remained too sick to govern.
Acting President Jonathan assumed executive powers in February and has since appointed a new cabinet and his own team of advisers.
Under the terms of the constitution, Jonathan will be sworn in as head of state and will then appoint a new vice president. The pair will complete the unexpired presidential term until elections due by April 2011.
It is unclear if Jonathan, who is from the southern Niger Delta, will run for president in the polls because of an unwritten agreement in the ruling party that power rotates between north and south. The next four-year term is due to go to Yar'Adua's predominantly Muslim north.
Jonathan's choice of vice president will be key. Should he decide not to run, his deputy -- likely to be a northerner -- is seen as a likely presidential candidate for the ruling party.
Sworn in pledging respect for the rule of law, Yar'Adua was initially seen by many Nigerians as a breath of fresh air after eight years of former president Olusegun Obasanjo, an overbearing ex-military ruler with a penchant for disregarding court orders and legal detail.
He was Nigeria's first university-educated leader and won victory in April 2007 polls which, though marred by intimidation and ballot-stuffing, marked the first transfer of power from one civilian president to another since independence in 1960.
But the optimism quickly faded.
Yar'Adua earned the nickname "Baba Go-Slow," a reference to the local term for Nigeria's crippling traffic jams, for what critics said was slow progress on everything from economic reforms to restoring the shambolic energy sector.
His biggest achievement was in the restive Niger Delta, the heartland of Africa's biggest oil and gas industry.
Militant attacks rumbled on during the early part of his tenure, but his offer of amnesty last year led thousands of gunmen to lay down their weapons and brought more than six months of relative peace in the region.
(Additional reporting by Chijioke Ohuocha; Writing by Nick Tattersall; Editing by Michael Roddy)