President Buhari has spent last two weeks in London hospital.
Nigerian president Muhammadu Buhari has requested parliament to extend his medical leave, indefinitely, according to a statement released by his office on 5 February.
Buhari had been due to return to Nigerian capital Abuja on 6 February but was advised by doctors to stay in London where he has been undergoing "routine medical check-ups" since arriving in Britain on 19 January.
Vice-president Yemi Osinbajo has assumed presidential responsibilities since the departure of the 74-year-old Buhari, whose return date and illness remain unclear.
Political analysts suggest that Buhari's extended leave could further erode confidence in his administration's management of a worsening economy and ongoing conflict with Boko Haram Islamist extremists in northern Nigeria.
Buhari's absence has even generated social media rumours of his death, a claim denied flatly by the president's aides. Certain Nigerian media outlets have also alleged that Buhari requires major surgery but that his cabinet has refused to let him go for the four months required over concerns that he would lose power during such a prolonged period away.
Last June Buhari spent 10 days in London, a week after his inauguration as Nigerian president, where he received specialist treatment for an ear infection. In the past the president has railed against “frivolous” medical tourism, claiming it lost Nigeria about $1 billion each year.