Zambia has officially charged former president Rupiah Banda for abuse of authority over a Nigerian oil deal, a government spokeswoman has said.

Ex-leader Rupiah Banda was arrested on Monday over a week after he was stripped of presidential immunity, an investigator said.

Banda, who has been accused of misappropriating more than $11m during his three years in office, was arrested and then later released on a bond, said Namukolo Kasumpa, a spokeswoman for the government's investigation team.

He will appear in court again on Tuesday, she said.

Banda, who led Africa's top copper producer from 2008 to 2011, has maintained his innocence.

The former president was questioned for nearly three hours after his arrest, his lawyer Sakwiba Sikota said, adding that Banda had done nothing wrong.

Banda later appeared before supporters telling them to remain calm and that he would win his case in court.

Banda was defeated in 2011 by rival Michael Sata, whose government has launched several high-profile corruption probes into deals struck by the former administration.

Source: Reuters