Ailing Buhari returns to Nigeria

President Muhammadu Buhari returned to Nigeria on Friday, his office said, after a three-day absence on medical grounds.

"President @MBuhari is back in Abuja. He arrived this evening from London," the presidency wrote on its Twitter account.

The 75-year-old former military ruler, who last year spent some five months receiving treatment in the British capital, had left on Tuesday to see his doctor there.

The move stoked fresh doubts about the president's health and his ability to campaign for re-election at polls scheduled for February next year.

Nigeria's main opposition Peoples Democratic Party (PDP) said Buhari was clearly unwell and unfit to govern.

Buhari has not disclosed the exact nature of his condition, saying only that he had "never been so ill" and disclosing that it involved blood transfusions and a battery of tests.

The PDP has previously claimed he was being treated for prostate cancer. Buhari has said those claims were untrue.

The health of the president is a sensitive issue in Nigeria following the death in office in 2010 of then president maru Musa Yar'Adua , which followed months of treatment abroad and sparked months of political turmoil.