Dhaka, April 26 -- Top Indian carriers Air India and IndiGo are facing longer flight times and increased fuel costs after Pakistan closed its airspace to Indian airlines.

The restriction follows escalating tensions between the two countries over a deadly militant attack in Indian-administered Kashmir.

India has blamed Pakistan-based elements for Tuesday's assault in Pahalgam, which left 26 people dead. Pakistan has denied any involvement.

In response to the incident, both countries have imposed a range of retaliatory measures. India has suspended a critical river water-sharing treaty, while Pakistan has closed its airspace to Indian airlines.

However, international carriers are not affected by this ban.

A Civil Aviation Ministry sour...