BRUSSELS (Updated 2) - NATO is keeping up the pace of air strikes in Libya despite the use of human shields by Muammar Gaddafi's forces as a tactic in fighting rebels, the Western military alliance said on Wednesday. NATO, accused by the head of Libya's rebel army of being too slow to order air strikes to protect civilians, said it had not lowered its sights. The besieged Libyan city of Misrata, the only major town in western Libya where the revolt against Gaddafi has not been crushed, is still top priority, NATO spokeswoman Carmen Romero said. "The situation on the ground is constantly evolving. Gaddafi's forces are changing tactics, using civilian vehicles, hiding tanks in cities such as Misrata, and using human shields to hide behind," she said. Despite that, "the pace of our operations continues unabated. The ambition and the position of our strikes has not changed," Romero said. "Misrata is our number one priority." The head of Libya's rebel army earlier accused the Western alliance of being too slow to protect civilians in Misrata, which is under daily attack by Libyan army tanks and snipers. Romero also reiterated NATO's position that it had destroyed 30 percent of Gaddafi's military capacity. NATO leads air strikes on Gaddafi's military infrastructure and polices a no-fly zone and an arms embargo, roles it took over on March 31 from a coalition led by the United States, Britain and France.