The United States has used drones repeatedly to attack al-Qaeda militants in Yemen. Last September, a U.S. drone killed U.S.-born cleric Anwar al-Awlaki, described by U.S. officials as “chief of external operations” for al-Qaeda in Yemen. AL ARABIYA – AGENCIES Air raids overnight on al-Qaeda strongholds in south Yemen killed at least 15 people, a tribal official said on Tuesday, adding that four strikes had been carried out on two positions. The attacks on the extremists, who have taken advantage of political turmoil in the country to overrun swathes of south Yemen, took place in the Loder and al-Wadih areas of Abyan province, the official said. “We think they were carried out by American planes,” another tribal source told AFP, speaking on condition of anonymity and without elaborating. A tribal leader said at least four of those killed were local al-Qaeda leaders. Residents said no civilians were hurt in the air strike. The United States has used drones repeatedly to attack al-Qaeda militants in Yemen. Last September, a U.S. drone killed U.S.-born cleric Anwar al-Awlaki, described by U.S. officials as “chief of external operations” for al-Qaeda in Yemen. The latest attack could deal a blow to al-Qaeda which has exploited unrest and protests against President Ali Abdullah Saleh to strengthen its hold on remote areas in southern Yemen in recent months, according to Reuters. An opposition-led government has been set up in Yemen after Saleh agreed in November to transfer authority to his deputy ahead of presidential elections in February. But protests have continued and activists are pressing on with demands that Saleh be tried for alleged killings of demonstrators and that the government is purged of members of his family. The deteriorating security situation in Yemen, caught up in an Arab pro-democracy uprising unleashed a year ago, has raised alarm including at the U.N. Security Council of a growing presence of al-Qaeda militants in lawless areas in the south and east of the country. In mid-January the extremists made a significant advance towards the capital Sana’a when more than 1,000 al-Qaeda fighters swept into the town of Rada and held it for nine days. They bowed to tribal pressure and withdrew from the town, 130 kilometers (80 miles) southeast of Sana’a, after authorities pledged to free 15 militants. The New York Times reported in June that the United States had stepped up its attacks on militant suspects in Yemen with armed drones and fighter jets. Saleh is in the United States for medical treatment after being seriously wounded in a bombing at the presidential palace in Sana’a in June. In November, after 10 months of bloody protests, he signed a deal by which he transferred constitutional powers to his deputy who is the sole candidate for next month’s presidential polls.