A severe heatwave hit Yemen's southern provinces controlled by the government, killing seven citizens within a week, a medical official told Xinhua on Wednesday.

Seven citizens died as a result of the heatwave that overwhelmed the southern province of Lahj in addition to the repeated power outages, the local medical source said on condition of anonymity.

"The emergency department at Lahj's public hospital received around seven cases who all died due to lack of electricity in their houses within this week," the source said.

"The victims were all elderly people suffering some diseases who fell down in a faint and then died due to the high temperature in Lahj," he added.

Sources at other hospitals in Lahj province confirmed that many cases were admitted to the emergency centers after suffering heat stroke and dizziness.

According to Yemeni meteorologists, the temperature reached 40 degrees in the country's southern port cities including Aden.

Stations of the old electricity corporation in Lahj were partially collapsed due to lack of maintenance, causing an increase of the power outages that reached more than 18 hours a day.

The impoverished Arab country has been locked into a civil war since the Iranian-backed Shiite Houthi rebels overran much of the country militarily and seized all northern provinces, including capital Sanaa, in 2014.

Saudi Arabia leads an Arab military coalition that intervened in Yemen in 2015 to support the government of President Abd-Rabbu Mansour Hadi after the Iranian-backed Houthi rebels forced him into exile.