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.
Interview with Newton Kanhema of the Zimbabwe Independence Assistance Network talks about Zimbabwe's Prime Minister Morgan Tsvangirai's U.S. visit.