General Mohammed Ali-Roqn, commander of the army's 122 brigade, along with eight other soldiers were killed in battle in Al-Jawf province Sunday while trying to reclaim positions lost months ago, the sources said.

The rebels also suffered casualties, the military source added without elaborating.

Huthi rebels took control of the capital of the northern province of Al-Jawf earlier this year -- a strategic advance that means they now threaten oil-producing Marib province.

Yemen's vice president, Ali Mohsen al-Ahmar, in a statement carried by the official Saba news agency, said Roqn was killed "while conducting military operations" in Al-Jawf.

Two government troops were killed and four others wounded in a Huthi missile attack on a military base in Marib, east of Sanaa, a government official said.

Renewed clashes also broke out in Al-Baida -- which is under nominal government control -- between loyalist forces and the Huthis, who have launched offensives against Al-Qaeda militants in the province.

Al-Qaeda in the Arabian Peninsula -- considered by the United States as the radical group's most dangerous branch -- has carried out operations against both the Huthis and government forces.

AQAP on Saturday executed a dentist in Al-Baida accused of spying for the government and guiding US drone strikes targeting the Islamist extremists.

The government and rebels have been locked in a five-year-old war that has killed tens of thousands -- triggering what the UN terms the world's worst humanitarian crisis.

Fighting has carried on despite repeated calls for a ceasefire as part of global efforts to combat coronavirus, which health agencies fear could become a disastrous outbreak in impoverished Yemen.

More than 1,800 cases of COVID-19 have been confirmed in Yemen, including 530 deaths.