Nigerian President Muhammadu Buhari extended his stay in London pending the result of health tests, presidential spokesman Femi Adesina said in a statement on Sunday.
The president has written to the National Assembly "informing them of his desire to extend his leave in order to complete and receive the results of a series of tests recommended by his doctors," Adesina said.
Buhari had been "advised to complete the test cycle before returning," he added.
Sunday's statement deepened suspicions of Buhari's health among many Nigerians, who believe his condition may be worse than authorities are letting on.
However, another spokesman for the president told Reuters news agency that the president "is not in any serious medical condition" in an attempt to provide assurances of the president's health.
Former President Goodluck Jonathan, Buhari's predecessor, was sworn in three months after the untimely death of President Umaru Yar'Adua in 2010, which triggered bitter political infighting in the ruling party.
Vice President Yemi Osinbajo has taken over some responsibilities in Buhari's absence as the country faces a humanitarian crisis caused by the Boko Haram militant group's insurgency in the Lake Chad region that threatens millions of citizens.
ls/bw (Reuters, AFP)