The airspace was closed for two hours between 1:00 PM and 3:00 PM, according to a NOTAM (notice to airmen).
Airlines said they where informed about the closure only this morning, which gave them little time to reschedule their flights, especially the incoming international ones.
Departures from the IGI Airport were re-scheduled by several carriers, they said.
"We received the NOTAM around 8 AM and hence we have to reschedule the departures and arrival," an airline official said.
According to officials, the closure has been done for re-calibration of the radar communication system of the IAF.
