All Nigerian ministers, ambassadors, agency heads and other political appointees should resign on or by May 16 if they decide to join the country's 2023 election race, the secretary to the government of the federation said in a statement on Thursday.

The statement follows one from President Muhammadu Buhari on Wednesday and makes clear that this includes central bank governor Godwin Emefiele, who has said he would seek the ruling party's presidential ticket.

Nigeria's political parties are running primary elections later this month and must pick their candidates by June 3.