An official of the newly-recruited security forces was killed by unknown gunmen in Yemen's southern port city of Aden on Monday, a government official said.

"Two masked gunmen opened fire and assassinated a security official named as Abu Raghed while he was driving his vehicle in the northeastern parts of Aden," the local government source said on condition of anonymity.

The gunmen escaped to unknown whereabouts after assassinating the security official who was leading a key checkpoint in the area, the source said.

He added that a security unit arrived in the area and began a search operation to capture the assailants.

No group has claimed responsibility for the recent assassination incidents yet, but the drive-by shooting attacks were blamed on the Yemen-based al-Qaida branch.

Politicians and high-ranking southern security commanders have been the prime targets in such armed attacks launched by unknown gunmen in recent months particularly in Aden and neighboring provinces.

The impoverished Arab country has been locked into a civil war since the Iran-backed Shiite Houthi rebels overran much of the country militarily and seized all northern provinces, including the capital Sanaa, in 2014.

Saudi Arabia leads an Arab military coalition that intervened in Yemen in 2015 to support the government of President Abd-Rabbu Mansour Hadi after Houthi rebels forced him into exile.