At least 15 soldiers loyal to Yemen’s government have been killed, officials in the south of the country say.
The soldiers were reportedly ambushed in the town of Ahwar in Abyan province, that was seized by al-Qaeda in February.
Officials blamed al-Qaeda for the ambush but the organisation’s local wing denied this, Reuters reports.
Al-Qaeda has seized more territory in Yemen in the past year as the country’s war continues.
Seventeen other captured soldiers were wounded but still alive, reports say.
Over the past year, the Houthi rebel movement and military units loyal to the former president have been battling a US-backed, Saudi-led coalition supporting the internationally-recognised government.
The United Nations says almost 6,300 people, half of them civilians, have been killed in the fighting.
UN-backed peace talks between the warring factions are due to begin in Kuwait on 18 April.
The so-called Islamic State group (IS) has made gains across Yemen in that time, as has al-Qaeda in the Arabian Peninsula (AQAP), most notably seizing the port city of Mukalla in April last year.
A report by Reuters this week said AQAP now had 1,000 fighters in the city, and brings in revenue of $2m (£1.4m) from the port every day. The group is also in control of 600km (370 miles) of coastline, the report said.