Pakistan's air force on Monday scrambled fighter jets over several major cities in a sign of increased "vigilance", following last month's deadly attacks on India's financial centre Mumbai. "In the current environment, PAF has enhanced its vigilance," chief air force spokesman Air Commodore Humaun Viqar Zephyr said. Residents in the capital Islamabad, the nearby garrison city of Rawalpindi and the eastern city of Lahore made panicked telephone calls to media outlets to ask about the low-flying fighter jets. Relations between nuclear-armed Pakistan and India have deteriorated in the wake of the Mumbai attacks, which left 172 dead including nine of the gunmen. Earlier this month, Islamabad accused India's air force of violating its airspace over Lahore and the Pakistani-administered part of Kashmir. The banned militant group Lashkar-e-Taiba -- which India blames for the Mumbai attacks -- is known to be active in both areas. New Delhi quickly denied the accusations.