Finance Minister, Okonjo-Iweala's mother, Prof Kamene Okonjo freed by kidnappers

The mother of Nigeria's Finance Minister Ngozi Okonjo-Iweala has been released five days after she was kidnapped, Delta state governor Emmanuel Uduaghan has told the BBC.

Kamene Okonjo, an 82-year-old retired professor, was seized from her home in southern Nigeria on Sunday.

It is not clear if Mrs Okonjo was held for political or financial gain.

Dozens of people were reportedly detained on Thursday during the search for Mrs Okonjo.

Earlier this week finance ministry spokesman Paul Nwabuikwu said that Mrs Okonjo-Iweala had been threatened recently.

He confirmed Mrs Okonjo's release, but gave no further details, AP news agency reports.

Police spokesman Frank Mba told the AFP news agency Mrs Okonjo was "in good health".

Mrs Okonjo-Iweala, 58, is an internationally respected economist who has led a high-profile campaign to clean up corruption in Nigeria, particularly in a controversial fuel subsidy programme.

Mrs Okonjo is a medical doctor and retired professor of sociology at the University of Nigeria in Nsukka. Her husband, Obi Chukwuka Okonjo Agbogidi, a retired professor of economics, is the traditional ruler of the Ogwashi-Uku kingdom in Delta State.