The official, who requested anonymity, said the jihadists were killed in air strikes that targeted buildings in the city of Zinjibar, including an intelligence and special forces headquarters occupied by the militants.
Several people were also wounded and taken to a hospital in the nearby town of Jaar, the official said.
An abandoned army weapons factory in Jaar which the jihadists had taken over was also hit, the official added, but was unable to say if there were any casualties.
It was not immediately clear if anyone was killed or injured.
More From This Section
Al-Qaeda in the Arabian Peninsula (AQAP) has taken advantage of Yemen's war between Iran-backed rebels and pro-government forces backed by a Saudi-led Arab coalition to expand in the south.
AQAP, which has long been entrenched in Yemen, is regarded by Washington as the network's most dangerous branch, and it has carried out deadly attacks on the West in the past.
Last week a US air strike on an AQAP training camp in Hajr, in the southeastern province of Hadramawt, killed 71 fighters, according to provincial officials.
The Saudi-led coalition launched its intervention in Yemen a year ago against the Huthi rebels but it has recently turned its guns on jihadists in southern Yemen.