Sanaa, Yemeninfo-iconInternetinfo-icon services returned to Yemen on Tuesday after a four-day outage caused by deadly coalition air strikes that marked a dramatic uptick in the seven-year warinfo-icon.

Web monitor NetBlocks said internet was "being restored" in the country and AFP correspondents in the capital Sanaa and port city Hodeida reported they were back online shortly after midnight.

"Connectivity collapsed after a series of deadly airstrikes. The incident severely limited independent mediainfo-icon and human rightsinfo-icon monitoring efforts," NetBlocks said.

An air raid by the Saudi-led coalition targeted a telecom facility in Hodeida late on Thursday in an attack that was blamed for knocking out the internet nationwide. At least three children playing nearby were killed.

The strike coincided with an attack on a prison in rebel-held Saada which left at least 70 people dead and wounded more than 100 more. The Saudi-led coalition denied bombing the prison.

The internet outage affected emergency operations after the strikes, where rescuers scrabbled through the rubble for survivors and the hospitals in Saada were overwhelmed.

They followed a deadly drone-and-missileinfo-icon assault by Yemen's Iraninfo-icon-backed rebels on the United Arab Emiratesinfo-icon capital Abu Dhabiinfo-icon, which drew international condemnation and threats of reprisals.

Two more rebel missiles were intercepted over the city on Monday. The UAEinfo-icon is part of the coalition fighting on behalf of Yemen's internationally recognised government.