Nigeria's President Muhammadu Buhari has given ammunition to critics who call him "Baba Go-slow" after admitting that he failed to sign a continental free-trade agreement because he is a "slow reader".

Mr Buhari said he intends to sign the agreement, reached by African leaders at a summit in Rwanda in March, soon.

“In trying to guarantee employment, goods and services in our country, we have to be careful with agreements that will compete, maybe successfully, against our upcoming industries,” Mr Buhari said at a news conference on Wednesday, Reuters news agency reports.

President Buhari with South Africa's President Cyril Ramaphosa

“I am a slow reader, maybe because I was an ex-soldier. I didn’t read it fast enough before my officials saw that it was all right for signature. I kept it on my table. I will soon sign it,” he added.

Mr Buhari was speaking during a visit to Nigeria by South Africa's President Cyril Ramaphosa.

Mr Ramaphosa had earlier told Nigerian business leaders that South Africa saw huge benefits from the continental free trade deal and that a draft agreement relating to the movement of people was being reviewed.

This was Mr Ramaphosa's first visit to Nigeria since he became president in February.

He said South Africa wanted closer relations with Nigeria. The two countries have the biggest economies in Africa.