SANAA- Three suspected al-Qaida militants were killed in Maarib province, east of the Yemeni capital Sanaa, in what local officials and tribal sources said was a strike by a US drone late on Thursday.They said the suspects were hit as they were traveling in a car in the Wadi Obaida area, in the oil-producing Maarib province. Several explosions were heard, witnesses said, after which they saw a car on fire with three burnt bodies inside it.The United States has stepped up drone strikes as part of a campaign against al-Qaida in the Arabian Peninsula (AQAP), regarded by Washington as the most active wing of the network.Yemen, AQAP's main stronghold, is among a handful of countries where the United States acknowledges using drones, although it does not comment on the practice.