"Al-Qaeda assailants carried out simultaneous attacks against three military positions in Rada" in Bayda, an extremist stronghold, the official told AFP.
Ten soldiers were killed and others wounded, while some of the attackers also died, including one wearing an explosive belt who was killed by soldiers.
The attacks were followed by clashes between the army and gunmen.
In December, a drone attack killed 17 people, mostly civilians in a wedding motorcade in Rada, triggering condemnation of drones operated in the region by the United States and sparking protests in the impoverished Arabian Peninsula country.
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Al-Qaeda in the Arabian Peninsula (AQAP) has been blamed for most of the increasingly common hit-and-run strikes targeting military personnel and officials.
The jihadist group rarely claims responsibility for such attacks, but did admit it was behind a brazen daylight assault on the defence ministry in the capital Sanaa that killed 56 people on December 5.
AQAP took advantage of a decline in central government control during Yemen's 2011 uprising to seize large swathes of territory across the south.
The militants were driven back in June 2012 by a military offensive and the group has been further weakened by US drone strikes.