ISLAMABAD: Pakistan has extended a ban on Indian-registered aircraft from using its airspace until late February, the Pakistan Airports Authority said on Wednesday, prolonging restrictions that have disrupted flight routes for Indian airlines. Pakistan first imposed the restriction on April 24 as part of a series of tit-for-tat measures announced by both countries days after an attack in Indian-administered Kashmir. New Delhi blamed the attack, which killed 26 tourists, on Pakistan. Islamabad denied any involvement and called for a credible, international investigation into the attack.