Nigeria's ailing President Umaru Yar'Adua returned home after a three-month stay in a Saudi hospital which triggered an unprecedented power vacuum in Africa's most populous country.
The country's ambassador to Riyadh said that Yar'Adua flew back home after a marked improvement in his condition.
The 58-year-old had been treated for a heart condition at a hospital in Jeddah.
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"Yes he has returned to Nigeria. His condition has improved tremendously," Nigeria's ambassador to Saudi Arabia, Abdullah Aminchi, told AFP.
Officials quiet on return
Officials in Nigeria have made no public comment about Yar'Adua's return which took place in the dead of night after a 93-day absence.
However a member of Yar'Adua's entourage confirmed that the president was back at his presidential villa in the capital Abuja.
"The president arrived early this morning but I have not yet had access to him," the senior official told AFP on condition of anonymity.
An AFP correspondent saw two planes land in succession -- one of them believed to be an air ambulance -- amid heavy security at the presidential wing of the international airport in Abuja.
A white ambulance and several sports utility vehicles with black tinted windows drove to meet the plane.
Armed soldiers were deployed at strategic points along the airport road and a bus parked nearby bore the "brigades of guard" inscription denoting the elite military unit that guards the head of state.
Convoy leaves airport
A convoy of 23 vehicles -- including the ambulance -- accompanied by a full presidential escort left the airport and was seen driving towards the direction of the Yar'Adua's official residence, Aso Rock Villa.
The president was taken ill last November and flown out to Jeddah's King Faisal clinic for treatment for pericarditis, an inflammation of the membrane covering and protecting the heart.
He has not been seen in public since then and has only given one brief interview.
Questions unanswered
As Yar'Adua had made no provision for who should take charge during his stay in Saudi Arabia, his lengthy absence from the helm of a major oil exporter caused disquiet both at home and abroad.
However some of the tension was eased when parliament voted on February 9 to hand over power to Vice President Goodluck Jonathan.
He moved swiftly to assert his authority, including conducting a cabinet reshuffle.
Yar'Adua's loyalists were initially reluctant for a transfer to be formalised but a split emerged in cabinet ranks as international powers, including the European Union and United States, voiced their unease.
Jonathan's elevation won widespread international support, including from the African Union which warned the army to support the handover.
Nigeria has a long history of coups and military leadership, and only returned to civilian rule a little over a decade ago.
Yar'Adua's future uncertain
It was not immediately clear when Yar'Adua would take the helm again although his absence was to be discussed on Wednesday at the weekly cabinet meeting.
Some political activists have called on the government to state that Yar'Adua is too ill to remain in office following his protracted hospitalisation.
The debate around the crisis arising from Yar'Adua's absence brought to the fore the political battle over the delicate regional power balancing act in Nigeria.
Under an unwritten rule, the presidency traditionally switches between the north and the south at every two elections.
Yar'Adua is from the predominantly Muslim north and Jonathan from the mainly Christian south.
