ABU DHABI: Years of setbacks have weakened the once mighty Yemeni branch of Al-Qaeda, but the militants are seizing the opportunity to regenerate while the government and Huthi rebels are locked in a fight to the death in the north.

Government security officials and tribal leaders told AFP that the fierce battle for Marib, which has raged for the past month, is creating a security vacuum that is being exploited by the militants.

Once seen as the most potent Al Qaeda franchise, they have suffered multiple defeats in the past three years, leaving them deprived of territory and fighters, and with mystery surrounding the fate of the leadership.

"The governorate of Marib has been AQAP's main stronghold for years," said one intelligence official.

While the main combatants in Yemen's six-year war sustain heavy losses in an effort to control Marib city, Al-Qaeda in the Arabian Peninsula remains "at ease" elsewhere in the region where it retains strong influence in villages and small towns.

"As others get busy fighting, they are training fighters again, planning, rebuilding relations" with local tribes and chasing "financial support" from local communities, the official added.

Marib city, the capital of the oil-rich governorate, is the last northern stronghold for the internationally recognised government which is backed by a Saudi-led military coalition.

The Huthis control the rest of the north after years of conflict which has plunged Yemen into the world's worst humanitarian crisis.

"The war in Marib could be ending the maximum pressure campaign that almost wiped (AQAP) out" in Yemen in the last few years, another Yemeni intelligence official said.