Tribesmen say a U.S. drone strike has killed three suspected al-Qaida militants in southern Yemen.

They say the strike, believed to be the first this year, hit the militants' vehicle while they were traveling in Shabwa province.

The tribesmen spoke on condition of anonymity because of security concerns. It was not immediately possible to verify their account. U.S. officials rarely comment on the covert drone program.

Al-Qaida in the Arabian Peninsula has long been seen by Washington as the global network's most dangerous branch. It has expanded its reach over the past year as Yemen has been mired in conflict between the internationally recognized government and Shiite Houthi rebels.