India, Jan. 15 -- Iran temporarily shut its airspace early on Thursday amid tensions over Tehran's crackdown on nationwide protests, forcing airlines to reroute flights and causing delays on key international routes linking India with West Asia and Europe, government officials told HT.

The Tehran Flight Information Region (FIR) was closed to all flights around 3:45am IST.

"During the closure, no overflights were permitted. Only international civil flights arriving into or departing from Iran with prior permission from the Iran Civil Aviation Authority (CAA) were allowed," an official in the know of the development said.

"Delhi ACC (Area Control Centre) was informed of the closure by Lahore ACC (OPLA), which cited military escalation as...