Peace talks aimed at ending almost four years of civil war in Yemen have started in Sweden – and hailed by the UN’s envoy as an important milestone.

It’s a war which has triggered humanitarian disaster on a massive scale, with Saudi Arabia’s airstrikes and blockade widely scrutinised and condemned.

But the role played by their key ally, the United Arab Emirates, has gone largely unnoticed. Yet the UAE stands accused of conducting a dirty war on the ground.

Our foreign affairs correspondent Jonathan Rugman has been speaking to to a high profile former prisoner who accuses the UAE of running secret prisons and subjecting hundreds of people to torture.