A Yemeni rights group on Tuesday accused both sides in the country's civil war of arbitrary detentions, forced disappearances and torture of hundreds of people in the past four years in unofficial detention centres across war-torn Yemen.

There were around 170 detainees at the facility when the airstrikes hit on Sunday. The International Committee for the Red Cross said 40 wounded were being treated for injuries while the rest were presumed dead.

The office of the United Nations' human rights office says deaths among civilians due to Yemen's conflict have been "steadily mounting."