"The big jet is under repair. So, the president is using a small plane and there is a limit to the distance the small plane can cover," he told AFP. "The technical stop-over I talked about is that the journey from US to Abuja is broken into two," Mr Shehu added.

Last year, Mr Buhari, 75, spent months in the UK receiving treatment for an unspecified illness.

Meanwhile, Nigeria's ex-President Olusegun Obasanjo has accused Mr Buhari of a "mediocre performance" when he met Mr Trump. “For whatever the meeting was worth, President Buhari again bungled another opportunity to self-redeem. No wonder President Trump ordered him in a rather condescending manner to go back home and stop the killings going on in Nigeria!," Mr Obasanjo was quoted in a statement issued by his media aide, Kehinde Akinyemi.

Mr Obasanjo backed Mr Buhari in his bid for the presidency in 2015, but has refused to endorse him for a second term in elections due in February. Mr Obasanjo's statement said only three things came out of the meeting between Mr Buhari and Mr Trump:

* The US will continue to purchase less crude oil from Nigeria "and there is nothing Nigeria under Buhari can do" about it

* The US will export agricultural products to Nigeria "and Buhari’s government will encourage that"

* All the killings taking place in Nigeria by herdsmen are being done by expatriates trained by ex-Libyan leader Muammar Gaddafi "and no Nigerian is to blame and Buhari cannot do anything to stop it".

Mr Buhari has not responded to Mr Obasanjo's criticism.