ABUJA (Reuters) - Nigerian President Muhammadu Buhari will travel to London on Sunday night for follow-up medical tests, handing over power to his deputy Yemi Osibanjo, his office said. 

FILE PHOTO - Nigerian President Muhammadu Buhari speaks during German President Joachim Gauck's visit to the State House in Abuja, Nigeria February 11, 2016.  REUTERS/Afolabi Sotunde/File Photo

Buhari, 74, returned to Nigeria two months ago after receiving medical treatment in Britain.  Officials have refused to disclose details of his medical condition. 

The president met on Sunday a group of 82 girls who had been released after being held captive for three years by Islamist militants, but he did not attend a cabinet meeting last Wednesday.  That was his third consecutive absence from the weekly meeting chaired by Vice President Yemi Osinbajo. 

“The length of the President’s stay in London will be determined by the doctors,” the president’s office said in a statement. 

“Government will continue to function normally under the able leadership of the vice president,” it said, adding that there was no cause for worry. 

Buhari, a former military ruler, returned home in March after nearly two months’ medical leave in Britain and said he would need more rest and then go back to Britain for follow-up tests. 

The president’s office said Buhari had notified both chambers of parliament of his trip, which will put Osinbajo formally in charge. 

Osinbajo, a lawyer who is seen as more business-friendly than Buhari, has played an active role in driving policy changes, chairing cabinet meetings during the president’s medical leave. 

Officials have sought to avoid a scenario seen in 2010 when political infighting broke out when then-President Umaru Yar’Adua was sick for months. 

Osinbajo was already given full powers to act during Buhari’s previous absence, in contrast to his predecessor Goodluck Jonathan who only took over after Yar’Adua’s death in 2010 ended a power vacuum.