Yemen's al Qaeda wing has stepped up operations in the southern flashpoint province of Abyan, its embassy in the United States said, taking advantage of a power vacuum as a rights group accused forces of unlawful killings U.S.-based group Human Rights Watch said in a statement on Saturday that Yemeni forces may have killed dozens of civilians in unlawful attacks while fighting an Islamist armed group in the southern province of Abyan since May 2011. In recent months, militants have seized two cities in Abyan, including its capital, Zinjibar. Some 54,000 Yemenis have fled Abyan since then, a government official said last week. A local official said 13 militants and six soldiers were killed in fresh clashes on Monday. Yemeni President Ali Abdullah Saleh appeared on Yemeni television on Thursday, the first time since he flew to Saudi Arabia for medical treatment following a June 3 assassination attempt and raid on his presidential compound. He had severe burns on his face and was visibly weaker but showed determination to hang on to power despite international pressure and six months of protests against his 33-year rule. Opponents of Saleh, who earned U.S. backing by portraying himself as a bulwark against al Qaeda, say he has deliberately let militants get the upper hand in Yemen's south to convince the United States and Saudi Arabia that only he stands in the way of a militant Islamist takeover. HRW said militants in Abyan called Ansar al-Sharia (Partisans of Islamic Law) may have unlawfully placed civilians at risk by deploying in densely populated areas and engaged in looting and other abuses. "As Yemeni government forces battle armed militants in Abyan, civilians are paying the price," Joe Stork, HRW deputy Middle East director, said. "Both sides need to be doing much more to protect civilians from harm, and the government should be investigating possible laws-of-war violations by its forces in Abyan," Stork said. The Yemeni government should promptly conduct impartial investigations into the allegations, and the responsible for violations of the laws of war that amount to war crimes should be prosecuted and the victims compensated, HRW said. The rights group said it had obtained accounts of the attacks in Abyan from 30 civilians who witnessed and fled the fighting, including several people wounded in attacks. Late on Friday, Yemen's embassy in Washington said militants of Al-Qaeda in the Arabian Peninsula (AQAP) had expanded their military operations in Abyan province. AQAP was "taking advantage of the fluid situation in the country and the protection offered by some sympathizers and a few tribal leaders," it said in a statement. AQAP claimed responsibility for a failed Christmas Day attack in 2009 aboard a U.S. airliner and an attempt in October 2010 to blow up two U.S.-bound cargo planes with explosive parcels. "Unfortunately this protection and cooperation has facilitated the recruitment and operations in some districts within that province," the embassy said. "On the other hand, tribesmen loyal to the state have recently demonstrated their unyielding cooperation with the ongoing military campaign to put a halt to AQAP's expansion into their territories," it said in the statement. The embassy said at least 70 soldiers and officers were killed and more than 300 wounded since the start of the current campaign late March. At least 50 militants were killed and dozens wounded during these operations, it said. Riyadh and Western powers are keen to put an end to the crisis in Yemen. They fear al Qaeda is exploiting a security vacuum in the south of the country, from where it has previously launched the failed attacks against the United States.