Yemen suffered a total blackout on Tuesday after gunmen in the eastern province of Marib sabotaged key power lines, the electricity and energy ministry announced.
"The act of sabotage at Kilometre 78 (48 miles east of Sanaa) suspended the entire national power and energy grid, including at Marib's gas plant, and cut power in all provinces," a ministry spokesman was quoted by the defence ministry news website 26sep.net as saying.
State news agency Saba quoted a spokesman as saying that power lines in Marib had come under attack twice.
Technical teams repaired the lines after the first assault before gunmen sabotaged them a second time and prevented technicians from fixing them again.
Tuesday's attack was the third of its kind this month, Saba said.
Attacks on power lines in Yemen are common and are often launched by heavily armed tribesmen as a lever to press for the release of jailed relatives or to support other demands.
Marib is also a stronghold of Al-Qaeda in the Arabian Peninsula (AQAP), seen by the United States as the extremist network's deadliest franchise, which has been targeted by an army offensive since April 29.
The absence of reliable electricity supplies further complicates the lives of Yemenis, who already suffer water and food shortages.
Sanaa residents have also faced severe fuel shortages for weeks, with motorists having to queue for hours at petrol stations.