The suicide bomber blew up his vehicle next to a military position recently set up by the Yemeni force in Shabwa province, the official told AFP, speaking on condition of anonymity.
Two vehicles belonging to the anti-jihadist force were destroyed in the attack, which left an undetermined number wounded while other soldiers were abducted by Al-Qaeda members supporting the suicide bomber, he added.
The official said the victims belong to an "elite unit" set up by the United Arab Emirates, one of the key partners in the Saudi-led coalition which intervened in Yemen in 2015 to support President Abedrabbo Mansour Hadi against Shiite Huthi rebels.
Al-Qaeda militants remain active in southern Yemen where they have exploited the security gap created by the conflict between Hadi's supporters and the Huthi rebels
The conflict in Yemen pits Huthi rebels and supporters of ex-president Ali Abdullah Saleh against forces loyal to the internationally recognised president Hadi.
The war has killed more than 8,000 people, mostly civilians, and wounded 44,500 since Saudi Arabia and its allies intervened against the rebels it says are supported by regional arch-rival Iran.