Nigeria's president has been pictured in London for the first time since he left his homeland almost 80 days ago.

President Muhammadu Buhari, 74, came to the UK for treatment for an unspecified illness.

On Sunday, he met governors from his party for lunch and was very cheerful, according to a government statement.

His absence has led to some anxiety in Nigeria, with some speculating that he might have died.

Others have worried he may not be able to return to duty.

The statement said the president "was very cheerful and has not lost any bit of his sense of humour".

Governor Rochas Okorocha, who was among the delegation, said President Buhari was asked about the rumours swirling around his health and laughed them off.

"President Buhari was completely unperturbed by the cocktail of lies. He, instead, sent his best wishes to Nigerians," he said.

He added that during the hour-long meeting, the president was fully engaged in discussions on home affairs.

Mr Buhari left Nigeria on 7 May - his second trip to the UK for treatment this year.

In his absence, he has given Vice-President Yemi Osinbajo full powers to act as head of state.

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Buhari's unhealthy start to 2017

19 January: Leaves for UK on "medical vacation"

5 February: Asks parliament to extend medical leave

10 March: Returns home but does not resume work immediately

26 April: Misses second cabinet meeting and is "working from home"

28 April: Misses Friday prayers

3 May: Misses third consecutive cabinet meeting

5 May: Appears at Friday prayers in Abuja

7 May: Travels to UK for further treatment

6 June: Buhari's wife says he is "recuperating fast"

12 July: Acting head of state says the president will be home "very soon"