Nigeria's main opposition presidential candidate, Muhammadu Buhari, has rejected claims that he did not obtain his school-leaving certificate.
Candidates must have it as a minimum requirement to run for office.
Mr Buhari said the governing party was trying to divert attention away from campaign issues such as unemployment, insecurity and corruption.
One paper has obtained a copy of his results from his former school showing he graduated in 1961 but failed maths.
Nigeria's Premium Times has uploaded a statement from the education ministry in his home state of Katsina and the 1961 University of Cambridge West African School Certificate result sheet for the Provincial Secondary School, Katsina.
It shows he passed English language and literature, Hausa language, history, geography and health science, but failed maths and woodwork.
Mr Buhari, who is standing for the All Progressives Congress (APC) party in the 14 February election, told journalists that he had asked his old school to make available a copy of the certificate showing that he had "passed the examination in the second division".
Muhammadu Buhari in focus:
Will the former general get the kiss of approval in February - his fourth attempt to win at the ballot box?
- Age 72
- Military ruler of Nigeria from 1984 to 1985
- Deposed in a coup
- Poor human rights record
- Seen as incorruptible
- Disciplinarian - civil servants late for work had to do frog jumps
"The issue in this campaign can't be my certificate, which I obtained 53 years ago," the AFP news agency quotes the 72-year-old former general as saying.
"The issue is the scandalous level of unemployment of millions of our young people, the state of insecurity, the pervasive official corruption which has impoverished our people and the lack of concern of the government for anything other than the retention of power at all costs."
Mr Buhari ruled Nigeria from January 1984 until August 1985, taking charge after a coup - and campaigned against corruption whilst in office.
However, his attempts to re-balance public finances by curbing imports led to many job losses and the closure of businesses.
He will be facing Pesident Goodluck Jonathan of the governing People's Democratic Party (PDP) in the elections, which look to be the closest fought since the end of military rule in 1999.