SANA'A: More than 100 influential religious clerics and tribal leaders called for the Yemeni president's ouster and elections to choose a new leader, adding their weight to the opposition movement seeking to end nearly 33 years of autocratic rule by Ali Abdullah Saleh. The president, who has clung to power despite four months of protests, is undergoing treatment in neighboring Saudi Arabia for serious burns and other injuries from a June 3 attack on his palace in the capital, Sana'a. His allies insist he will return to the country within days and resume his duties. The clerics' petition, obtained Saturday, demands elections within 60 days and says Saleh is unfit to return to his post. “President Saleh is unable to carry out his responsibilities. He must step down,” the statement said. Among the petitioners is Sheik Abdul-Majid Al-Zindani, the spiritual leader of the country's opposition party, Islah, and Yemen's most influential cleric. He has backed the anti-Saleh protesters since early on in the unrest. Others who have abandoned the Yemeni leader include top military commanders, powerful tribal chiefs and members of Saleh's ruling party. Many defected to the opposition in outrage at the killing of protesters. Yemen's crisis began when demonstrators inspired by successful uprisings in Egypt and Tunisia took to the streets in early February. The largely peaceful movement gave way to heavy street fighting when tribal militias took up arms in late May. Emboldened militants have also seized on the expanding disorder to take control of towns in southern Yemen, adding to fears that the Al-Qaeda offshoot in the country could end up with even more room to operate freely. Military and medical officials say government artillery shelling of an area in southern Yemen has killed 12 Al-Qaeda-linked militants and wounded three others. The officials said Sunday the shelling was concentrated on the Dufas area in Zinjibar, capital of Abyan province. Both spoke on condition of anonymity because they were not authorized to brief reporters. Militants are taking advantage of internal strife in Yemen to overrun parts of the country. Several days ago, warplanes attacked militant hideouts, killing several fighters. The government also shelled the areas. In response, the Ansar Al-Sharia group listed in a statement the names and ranks of 12 air force and army officers it said it intended to kill for taking part in the attack.