HOME AT LAST: Nigerian president Umaru Yar'Adua flies into Nigeria

Nigerian President Umaru Yar'Adua has arrived back in Abuja after three months in a Saudi Arabian hospital, renewing uncertainty over the leadership of Africa's most populous nation.

There was no immediate word on the physical condition of the 58-year-old leader and it was unclear whether he would be fit enough to resume office or whether Vice President Goodluck Jonathan would remain as acting head of state.

Mr Jonathan has since adopted the mantle of leadership, reshuffling ministers, pledging to tackle chronic power shortages and forge ahead with an amnesty in the oil-producing Niger Delta. Some politicians have said he could win support to run for president in elections due by April next year.

"The news of the president's arrival is reportedly causing a lot of anxiety in Abuja especially among politicians, many of whom had prepared themselves for a post Yar'Adua era," Nigerian newspaper NEXT said on its website.

The cabinet, which has twice passed resolutions that there are no grounds to declare Yar'Adua unfit to govern, is due to hold a weekly meeting later on Wednesday.

Splits have emerged between Yar'Adua loyalists and ministers who feel he should step aside.

Two planes arrived at the presidential wing of the Nnamdi Azikiwe international airport in Abuja, one of them met by an ambulance which left under a heavy police escort shortly afterwards, a witness said.

Soldiers lined the main road from the airport to the city, a standard manoeuvre when the president is travelling.

"He just landed at Abuja airport on a Saudi plane escorted by the presidential plane. He is on his way to the (presidential) villa now," one government source said.

Neither the government nor the presidency could be reached for comment. One presidency official said there was still uncertainty there about what the president's return from Saudi Arabia would mean.

The political implications of Yar'Adua's reappearance will depend on the state of his health.

Mr Jonathan could continue as acting president until such time as Mr Yar'Adua's health recovers and he is fit enough to resume office. Should his condition be so serious as to render him incapable of holding office, he could step aside, allowing Mr Jonathan to be sworn in as leader and name a new deputy.

Mr Yar'Adua has been receiving treatment for pericarditis, an inflammation of the membrane surrounding the heart that can restrict normal beating, and is also known to suffer from a chronic kidney condition.