Five soldiers were killed in an ambush in the southern province of Shabwa in the third attack of its kind this month blamed by security officials on the jihadists.
"Gunmen probably belonging to Al-Qaeda opened fire on an army vehicle in Habban in Shabwa province, killing five soldiers and wounding another," a security official said.
He added that the attackers then escaped.
Meanwhile, two soldiers were killed and two others wounded in a clash with gunmen in Sayun, in the southeastern Hadramawt province, another security official said.
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The army is reinforcing its presence on the outskirts of Sayun in preparation for an imminent operation against militants, the official said.
The defence ministry said "18 members of Al-Qaeda" were killed in this confrontation, adding that several others were captured, including a Saudi militant.
On Monday, four soldiers died in a ambushes in Hadramawt, and four policemen were killed on Saturday in an attack on a checkpoint in Shabwa.
Security services also blamed the two earlier attacks on Al-Qaeda in the Arabian Peninsula, which has been branded by Washington as the extremist network's deadliest franchise.
The group is active across several parts of Yemen, taking advantage of a collapse of central authority during a 2011 uprising that ousted veteran president Ali Abdullah Saleh.