Rupiah Banda, Zambia ex president, has been arrested in connection with a Nigerian oil deal, officials say.
Rupiah Banda is accused of stealing more than $11 million during his three years in office, Reuters news agency reports.
The former leader, who was stripped of presidential immunity earlier this month, was questioned for nearly three hours before being freed on bail.
Rupiah Banda denies the charges and says he is the victim of a witch-hunt. He is due in court on Tuesday.
Shortly after being released, Rupiah Banda addressed his supporters, telling them to remain calm and that he would win the case in court.
He lost 2011 elections to Michael Sata, whose government is investigating several high-profile deals made by Rupiah Banda’s administration amid accusations of corruption.
Rupiah Banda led Africa’s top copper producer from 2008 to 2011.