Mele Kyari, the group managing director of the Nigerian National Petroleum Company (NNPC), announced the death of Mohammed Sanusi Barkindo in a tweet on Wednesday morning.
He died at about 11pm on Tuesday night, according to Mele Kyari. The cause of his death was not disclosed.
According to reports, Barkindo was received by Nigerian President Muhammadu Buhari on Tuesday, and later gave a speech at the Nigerian Oil & Gas conference (NOG) which is still in session in the country's capital Abuja.
Barkindo has served as OPEC Secretary General since August 2016 and was expected to complete his term as the OPEC Secretary General on July 31.
Mohammed Barkindo was born in 1959 in Nigeria.