Nigerian President Muhammadu Buhari has headed to London for "follow-up medical consultation with his doctors" — though his administration has not elaborated on what, precisely, his doctors will be addressing. The visit comes as concerns simmer over the president's health, which has attracted speculation as he misses cabinet meetings and makes infrequent public appearances.

"The length of the President's stay in London will be determined by the doctors," Femi Adesina, the president's special adviser on media and publicity, announced on Facebook on Sunday. "Government will continue to function normally under the able leadership of the Vice President."

Adesina noted that Buhari had delayed a trip originally scheduled for earlier in the day, in order to welcome the 82 Chibok schoolgirls released by Boko Haram militants after years of captivity.

Adesina also pointedly told the Nigerian people "that there is no cause for worry," yet he left unmentioned the nature of the illness Buhari's doctors are examining.

As NPR's Merrit Kennedy reported last week, he has missed several recent cabinet meetings, ceding a leadership role in many day-to-day matters to his vice president. Earlier in the year, Buhari spent seven weeks of medical leave in the U.K. — again, for undisclosed reasons.

The absences have stirred enough worry among onlookers that Adesina felt compelled to post a follow-up. Just hours after announcing Buari's trip, he took to Facebook again with a statement by the National League of Veteran Journalists, which denounced "SCARE MONGERING" by "agents of destabilization using the so-called ill health of President Muhammadu Buhari as their ploy."

"This scare mongering is being fanned by those who want the old order to subsist so that they could feast on the national till unchallenged. The President did not hide his case when he took ill and sought medical assistance in Britain," read the statement, signed Secretary-General Ben Lawrence and past President Ajibade Fashina-Thomas.

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