Ansar al-Sharia group said on Twitter that its fighters had seized control of the camp of Battalion 19 in the province's Bihan district.
The group posted photos of nine soldiers allegedly captured by its fighters.
A local official, however, said that attack was carried out by armed tribesmen.
He said that one soldier was killed and four others were injured in the attack.
Yemen has been dogged by turmoil since pro-democracy protests forced autocratic President Ali Abdullah Saleh to step down in 2012 after 33 years in power.
According to the government, Al-Qaeda remains active in several parts of the country's south, from which it stages sporadic attacks on army and police personnel.