The SITE Intelligence Group said ’Jund Al Yemen’ (Soldier of Yemen) has posted a photograph of the bomber, named as Ahmad bin Saeed bin Umar Al Mashraji, also known as Abu Dujana Al Hadrawi.
The car bombing in the town of Sayun that also wounded 17 people, including 11 policemen, was to avenge the killings of several jihadists "with whose blood the hands of [government] soldiers have become stained," Jund Al Yemen said.
In the photograph, also carried by SITE received in Dubai, Mashraji is seen armed with a comrade in front of a black flag which reads "There is no God but Allah."
A Yemeni security official has blamed "extremist terrorists who use Islam as a cover" for the attack, which targeted a compound housing the Central Security and General Security networks.
Sayun, in the heart of Hadramut province, is 700 kilometres east of the capital Sanaa.
The country, which has sided with the United States in its "war on terror," has seen several attacks attributed to or claimed by the Al Qaeda network led by Osama bin Laden, who is originally from Yemen.
In October 2000, Al Qaeda militants on a small explosives-packed boat blew up an American warship, the USS Cole, in the southern port city of Aden, killing 17 US sailors.
The latest attack was initially claimed by a little-known group, the Islamic Jihad Organisation in Yemen, which said it was demanding five million dollars from the government to halt terror attacks.