"Three soldiers were killed in the attack on the first military zone in the Al-Qoton district, and the gunmen managed to get away," the source said, requesting anonymity as he was not authorised to brief the press.

"We suspect the gunmen belong to Al-Qaeda," the source added.

Al-Qaeda has flourished in Yemen as the country's civil conflict shows no sign of waning.

Al-Qaeda in the Arabian Peninsula (AQAP) extremists remain active in the vast region of Hadramawt, where a number of the group's leaders are based.

The United States has intensified its controversial air attacks on AQAP, which it considers the global jihadist network's most dangerous branch, since President Donald Trump took office in January.

Yemen's Saudi-backed government has for years battled Huthi rebels allied with Iran for control over the country, the most impoverished in the Arab world.

More than 8,000 people have been killed and 40,000 wounded since an Arab coalition led by Saudi Arabia joined the Yemen war in 2015, according to the UN's World Health Organization.