The picture shows the 74-year-old head of state sitting at a table with a group of people and smiling.
An apparent photo of Nigerian President Muhammadu Buhari was posted on Twitter Sunday, offering a rare glimpse of the ill leader since his departure for London for medical treatment in May.
Posted from the official Twitter account of the Nigerian presidency, the picture shows the 74-year-old head of state sitting at a table with a group of people and smiling.
According to the presidency, on Sunday afternoon Buhari received a delegation of "governors and leaders" from his All Progressives Congress (APC) party in London.
"The president sends his best wishes to all Nigerians. He will be back to Nigeria as soon as his doctors give the go-ahead," said the presidency in a separate tweet.
Buhari has spent most of this year in London receiving treatment for an unspecified medical condition.
In January and February, he spent almost two months in Britain and on his return in early March said he had never been as ill.
Buhari left for the British capital again on May 7 for a second round of medical treatment. No date was given for his return.
"The President was very cheerful and has not lost any bit of his sense of humour," said Imo state governor Rochas Okorocha in a press statement issued Sunday by presidential spokesman Femi Adesina.
"The party delegation spent more than an hour with President Buhari over lunch, and it was very clear from discussions that he followed developments at home very closely," Okorocha said.
The presidency has repeatedly rejected rumours that Buhari is terminally ill or even dead but has refused to disclose his illness or what treatment he is having.
The silence on Buhari's health has led to a flurry of speculation about his fitness for office and potential successor, prompting cryptic warnings from the president's camp.
Responding to the rumours in a Facebook post, Buhari's wife Aisha warned earlier in July that "the hyenas and the jackals will soon be sent out of the kingdom."
On Friday, Adesina, the presidential spokesman, posted an essay on Facebook titled "PMB (President Muhammadu Buhari) and the Descendents of Shimei" that condemned "filthy dreamers" who "wish the President dead."