Roy Bennett, a nominee for deputy minister of agriculture, was arrested at a Harare airport and charged with treason for allegedly plotting to kill Robert Mugabe, the Zimbabwean president.
The Movement for Democratic Change (MDC) party's statement described the charges against him as "scandalous" and "politically motivated".
Al Jazeera's Rory Challands reports.
Sudan's governemnt has accused Darfur's largest refugee camp of harbouring rebel fighters. The Kalma camp is the only one that is permanently protected by United Nations and African Union forces, but residents fear they may be driven out as the military threatens to take action. Al Jazeera's Hoda Abdel-Hamid reports from the camp.