Nigeria's first lady Aisha Buhari has said that her husband is not as sick as is being perceived.

She tweeted that President Muhammadu Buhari, 74, was continuing to "carry out his responsibilities" and has been meeting with ministers.

A group of prominent Nigerians called on Mr Buhari to take medical leave amid growing concern about his health.

In March, he returned from seven weeks of medical leave in the UK where he was treated for an undisclosed illness.when he returned home he said he had never been so ill in his life.

He has missed the last two cabinet meetings and uncharacteristically did not show up at last Friday's prayers at the mosque on state house grounds.

Mrs Buhari courted controversy last year when she said in a BBC interview that she would not back her husband's re-election unless he makes changes in his government, saying that it had been hijacked by a few people.

Responding to the comments Mr Buhari famously said that his wife belongs to the "other room".

Information Minister Lai Mohammed told the BBC that the president's health was "a personal matter" and that Nigerians have been kept aware of his condition.

'Take a rest'

Thirteen Influential civil society figures, including lawyer Femi Falana, political analyst Jibrin Ibrahim, and Transparency International Nigeria head Anwal Musa Rafsanjani said in a statement that the president's absence from the cabinet meetings, as well as the weekly Friday Muslim prayers, "has fuelled further speculation and rumours" about his medical condition.

The 13 said they felt "compelled" to ask Mr Buhari "to heed the advice of his personal physicians by taking a rest to attend to his health without any further delay".

Mr Buhari's personal assistant Bashir Ahmed said the president had met Justice Minister Abubakar Malami and other officials at the presidential villa on Tuesday as part of his official duties.

Last week, presidential spokesman Garba Shehu said Mr Buhari was "taking things slowly, as he fully recovers from the long period of treatment" in the UK.