Nigeria's President Muhammadu Buhari is recovering fast from an undisclosed illness and should be back in Nigeria soon, his deputy said on Wednesday, after a whistlestop trip to meet the ailing head of state in London.

Vice-President Yemi Osinbajo told reporters before a weekly cabinet meeting in Abuja that he had been in London on Tuesday to "check up on" the 74-year-old Buhari, who left for medical treatment in the British capital on May 7.
 "Of course I've been speaking to him on the phone and I thought it would be a good thing to go and see him and generally check up on how he was doing and also to brief him on developments," he said.

"We had a very good conversation on wide-ranging issues and he's in very good spirits. He's recuperating very quickly and he's doing very well."
The meeting lasted for "well over an hour", he said, adding: "We are expecting him (back in Nigeria) very shortly."

Osinbajo, who has been acting president since Buhari's departure, made no mention of the president's medical condition, which has led to growing calls for clarity about his fitness to govern.

The former military ruler has now spent nearly four months of this year out of the country and has not been seen in public for more than two months.

When he returned from a previous trip to London in January and February, Buhari said he had "never been so sick" and disclosed he had undergone blood transfusions and a battery of tests.