Nigerian President Muhammadu Buhari said on Thursday he does not know if he will seek re-election in 2019 and the decision is personal and also for Nigerians.

Buhari, 75, was speaking in a radio interview. He was elected in 2015 but spent much of 2017 in Britain being treated for an undisclosed ailment that left him visibly weakened. Some have questioned his willingness or ability to run again.

Adebayo Shittu, Nigeria's minister of communications who played a prominent role in Buhari's 2015 campaign, has said he would chair a group to support the re-election of the president and Vice President Yemi Osinbajo.

Such campaigns by supporters often pave the way in Nigeria for a president to declare his intention to run again.

Analysts say the fact that Shittu has discussed campaign arrangements with Buhari and then made it public is a sign that he may have given his approval.

Nigeria will hold presidential elections on February 16, 2019 and parties have between August 18 and October 7 this year to select their candidates.

In a blow to the president, Atiku Abubakar, a former vice president and key Buhari ally, quit the ruling All Progressives Congress in December and said he was prepared to run in 2019. Last month he joined the opposition People's Democratic Party.