* Yemen is home to one of most active al Qaeda wings
* Four attacks on militants in four days
* Discontent over drone attacks growing
SANAA, Jan 23 (Reuters) - At least six suspected al Qaeda members were killed in a U.S. drone strike in northern Yemen on Wednesday, local sources said, in an escalating campaign in which at least 20 Islamist militants have died this week.
The United States never comments on strikes by its pilotless aircraft, which it has used to track down militants in Yemen for years. The Yemeni government tolerates such strikes but usually does not comment on the U.S. role in specific incidents.
Washington has scaled up action against al Qaeda in Yemen, where the group exploited widespread anti-government unrest in 2011 to seize swathes of territory in the southern part of the country, before being driven out in a U.S.-backed offensive in June last year.
The sources said the drone strike targeted a vehicle travelling in rural areas near the capital Sanaa.
"The vehicle was totally destroyed and the corpses were burned beyond recognition," one source told Reuters.
U.S. drones have launched almost daily raids on suspected al Qaeda militants in Yemen since Saturday.
Shoring up stability and security in Yemen is a priority for the United States and its Gulf Arab allies because of its location next to the world's top oil exporter, Saudi Arabia, and to shipping lanes, and because it is home to one of the most active wings of al Qaeda.
Al Qaeda in the Arabian Peninsula (AQAP) is considered by Western governments to be one of the most dangerous arms of the global network founded by Osama bin Laden, and has attempted a number of attacks against U.S. targets.
Four suspected insurgents were killed in a strike at al-Jawf province, near the border with Saudi Arabia on Tuesday. On Monday, four suspected militants were killed in a drone strike in central Yemen, while another six were killed in two separate raids on Saturday and Sunday.
A further 10 suspected al Qaeda fighters died in an explosion in a house in southern Yemen on Sunday.
Air strikes have aggravated discontent among Yemenis, who say the strikes pose a threat to civilians in the area.
A Yemeni cabinet minister on Tuesday criticised drone strikes and urged a move to ground operations to avoid hurting civilians.
On Sunday armed tribesman, angry at what they said was a drone attack on an area inhabited by civilians, blocked the main road linking Maarib with Sanaa.
Earlier this month, dozens of armed tribesmen also took to the streets in southern Yemen to protest against drone strikes that they said had killed innocent civilians and fuelled anger against the United States. (Reporting by Mohammed Ghobari; Writing by Sami Aboudi; Editing by Myra MacDonald)