Hopes have been raised that a British human rights activist jailed illegally in Ethiopia could soon be released, after the country's prime minister announced the pardoning of political prisoners and the closure of a prison where he may have been detained and tortured.

Andy Tsege, 62, was abducted by Ethiopian security forces in 2014, having been tried and sentenced to death in absentia.

The Ethopian government claims he is a terrorist, while human rights campaigners say the father-of-three was illegally detained on politically motivated charges.

But in an unexpected announcement on Wednesday, Hailemariam Desalegn, the Ethiopian prime minister, said he would drop charges against political prisoners and also close the notorious Maekelawi Prison.

"Political prisoners that are facing prosecutions and are already under arrest will be released," Hailemariam said.

"And the notorious prison cell that was traditionally called Maekelawi will be closed down and turned into a museum."

It remains unclear whether Mr Tesge is among those due to be set free, but human rights campaigners say his release is long overdue and that he has been tortured by his captors.