By Asif Shahzad, Ariba Shahid and Fayaz Bukhari ISLAMABAD/SRINAGAR, India (Reuters) -Pakistan closed its air space for Indian airlines and rejected New Delhi's suspension of a critical water sharing treaty on Thursday in retaliation for India's response to a deadly Islamist militant attack on tourists in Indian Kashmir.

Tata-owned Air India and budget carrier IndiGo on Thursday issued travel advisories after Pakistan abruptly closed its airspace to all Indian-owned or Indian-operated airlines, triggering flight disruptions across several international routes.

Air India and IndiGo on Thursday said some of its international flights have been impacted by the Pakistan airspace closure, with the Tata Group-owned airline mentioning that its flights connecting North America, UK, Europe and Middle-East are likely to take an alternative extended route.