LAGOS, Nigeria (AP) — The family of the former oil minister is asking Nigerians to pray for her as she fights cancer and British allegations of corruption.

A statement Friday from Diezani Alison-Madueke's lawyer denied she was arrested in London last week and said she was "merely invited" to answer questions by Britain's National Crime Agency.

The agency confirmed only that it briefly arrested five unidentified people in a bribery and money-laundering investigation.

Nigerian newspapers reported Alison-Madueke had been arrested and released on bail.

The ex-minister has been in London for months since her party lost power and President Muhammadu Buhari took office in May promising to halt endemic corruption.

Nigeria's former Central Bank governor has alleged $20 billion in oil sales went missing in two years under Alison-Madueke's watch.

Nigerian media identified Alison-Madueke as the minister that the U.S. Justice Department told Buhari had looted $6 billion. Edo State Gov. Adams Oshiomhole was at the meeting and reported Buhari was given the name of the minister, but he did not identify the person.

Lawyer Oscar M. Onwudiwe denied allegations of corruption and media reports of the Madueke family's ownership of multimillion-dollar homes in Britain and the United States, denouncing "a deliberate and vicious campaign to demonize members of the Madueke family."

He said Alison-Madueke has been in London receiving months of chemotherapy and will undergo surgery next week.

"The family ... would plead with all reasonable Nigerians to pray for her recovery so that she can face these allegations and give account of her stewardship," the lawyer said.