Opposition leader Andargachew Tsege has appeared on Ethiopian state television, following his disappearance from Yemen last month.
BBC 9 July 2014 Last updated at 09:31 GMT
His UK-based wife Yemi Hailemariam told the BBC she was shocked to see him on television.
Yemen arrested Andargachew while he was in transit at Sanaa airport, and secretly handed him to Ethiopia.
In 2009, Andergachew was sentenced to death in absentia for planning to assassinate government officials.
Andergachew, a UK national, denied the charge.
He is secretary-general of Ethiopia's banned Ginbot 7 movement.
Ms Yemi said it was difficult to see footage of her husband.
"I switched it off quickly. I couldn't watch it," she said.
Ms Yemi said the UK should demand the immediate release of her husband.
"If they want to try him, they must go through the proper channels," she told the BBC.
Ginbot 7 says Andargachew had been on his way from the United Arab Emirates to Eritrea when he was detained at Sanaa airport.
Ginbot 7 (15 May) was named after the date of the 2005 elections, which were marred by protests over alleged fraud that led to the deaths of about 200 people.