Masked gunmen shot dead a senior intelligence officer in southern Yemen on Tuesday, local and security officials said.

Colonel Ahmed Barmadah, deputy head of the Political Security Office, the domestic intelligence service, was leaving his house in the port city of Mukalla in Hadramout province when gunmen on a motorcycle opened fire on him, the officials said.

No one claimed responsibility for the killing but a security official said he suspected that al Qaeda militants, who are battling the U.S.-backed government, were behind it.

Tuesday's attack was the latest in a series of killings targeting security officials and politicians in the impoverished and often chaotic Arabian Peninsula state.

Yemen's stability is a priority for the United States and its Gulf allies because of Yemen's strategic position next to top oil exporter Saudi Arabia and shipping lanes, and because it is home to a wing of al Qaeda.

Washington is worried that al Qaeda, entrenched in parts of Yemen, will use a power vacuum to launch attacks abroad, and has stepped up drone strikes on suspected militants with the backing of President Abd-Rabbu Mansour Hadi.

Yemen-based Al Qaeda in the Arabian Peninsula (AQAP) and other militant groups seized parts of the country during a revolt lasty year that ousted veteran strongman president Ali Abdullah Saleh in February.

The U.S.-backed military offensive earlier this year has driven the militants out of the areas they controlled but has not prevented them from launching attacks that have dealt damaging blows to the army and security apparatus.

On Saturday, 17 army officers and soldiers were killed in an ambush carried out by suspected al Qaeda insurgents. While in October, an Iraqi adviser to the Yemeni army and a Yemeni security officer working at the U.S. Embassy in Sanaa were gunned down by armed men.

Domestic intelligence chief Ghaleb al-Qamish is viewed as having remained neutral during the protests against Saleh but his agency has played a major role in the fight against al Qaeda. Suspected militant detainees are held in its prisons.