WASHINGTON: The White House on Monday warned that Al-Qaeda could take advantage of a power vacuum in Yemen and pushed for a transfer of authority by its key anti-terror ally President Ali Abdullah Saleh.Signs that Washington was edging away from the long-time Yemeni president came on another day of bloodshed when Yemeni security forces shot dead at least 17 protesters and Gulf states offered to mediate the crisis.”We are obviously concerned that in this period of political unrest that Al-Qaeda and other groups will attempt to take advantage of that power vacuum,” said White House spokesman Jay Carney.”That is one of the reasons why we urge political dialogue to take place and a timetable for this transition that President Saleh has talked about to be begun,” Carney said.The White House fie…