A U.S. drone airstrike on a vehicle east of Yemen's capital of Sanaa on Monday killed three suspected al-Qaeda militants and wounded two others, according to security officials.

The airstrike was the third to target al-Qaeda militants in the area since Saturday and indicated an uptick in the U.S. military battle against the terror organization in Yemen. On Saturday, two U.S. drone strikes killed eight people, including two known al-Qaeda militants, in Marib province.

The security officials said the five targeted Monday were travelling in a pickup truck when it was hit in Marib, about 40 kilometres outside its main city with the same name. Two were killed on site, while another died hours later of his wounds, according to the officials, who spoke on condition of anonymity because they were not authorized to brief the media.

Two of those killed were identified as Ali Saleh Toaiman and Qassim Nasser Toaiman. Both were members of the same clan and were among several hundred suspected al-Qaeda militants freed by authorities in April 2012 after several months in detention, the officials said.

The third was identified as Ahmed al-Ziadi, who is suspected of being an al-Qaeda leader in Marib.

All three are thought to have fought government forces in the southern Abyan province, where al-Qaeda militants gained a foothold before they were driven out last year.

Yemen's government, aided by the U.S., has waged a campaign against al-Qaeda's branch in Yemen. The group is considered among the world's most active, having planned a series of foiled or aborted attacks on U.S. territory.

Speaking to reporters last week, the head of national security in Yemen, Gen. Ali Hassan el-Hamdi, said that the nation on the tip of the Arabian Peninsula was co-operating with the international community to fight terrorism.

The United States rarely comments on its military role in Yemen, but has acknowledged targeting al-Qaeda militants in the past.