ADEN - The governor of Aden was killed by a car bomb on Sunday in Yemen's southern port city, in an attack that Islamic State claimed responsibility for.

People gather at the site of a car bomb attack that killed the governor of Yemen's southern port city of Aden December 6, 2015. Jaafar Mohammed Saad was killed on Sunday when a suicide bomber rammed his car into the governor's convoy in the western part of Aden city, residents and a local official said.  [Photo/Agencies]

A local official and residents said at least six members of General Jaafar Mohammed Saad's entourage also died in the attack, which targeted the governor on his way to work. Several other people were wounded.

The attack came in the Tawahi district of Aden, where President Abd-Rabbu Mansour Hadi has returned to oversee a war against Iran-allied Houthis.

Islamic State, in a statement posted on a messaging service, said it detonated a car laden with explosives as Saad's convoy passed by. The group promised more operations against "the heads of apostasy in Yemen".

The group also posted what it said were photos of the booby-trapped vehicle as a white van carrying Saad drove past, then two other photos of a huge ball of fire which it said were taken as the bomb exploded.

A local official and residents said earlier on Sunday a suicide bomber rammed his vehicle into the governor's car.

Islamic State's local branch has stepped up operations since the outbreak of civil war in Yemen, emerging as a forceful rival to Al Qaeda in the Arabian Peninsula (AQAP), the main militant group in the country in recent years.

Spectacular attacks have been launched on security bases and on mosques run by Houthi forces who control the capital, Sanaa. The Houthis, who follow the Zaydi branch of Shi'ite Islam, have been fighting a coalition of mainly Gulf Arab forces, which began air strikes against them in March.

The attack came a day after assailants killed a senior army officer and a judge who had presided over the trial of militants suspected in the bombing of the U.S. warship USS Cole in Aden in 2000, in two separate attacks in the city.

In October, four suicide bombers detonated car bombs at a temporary Yemeni government headquarters and two Arab coalition outposts, killing more than a dozen people.

"Foot-dragging in implementing security measures paves the way for hardliners to carry out such attacks," said Ashraf Ali Mahmoud, a local activist.