An anonymous call received at an airline call centre threatening to explode a bomb on Tuesday sparked a security alert at the Indira Gandhi International (IGI) airport here with police sanitising the facility.
The call centre of national carrier Air India received the telephone call at around 7 pm in which the caller threatened to trigger a bomb blast.
A senior CISF official said the call was "not specific" as to whether somebody was targeting a plane or the airport.
"The caller did not say where the bomb will be exploded. Security officials, at a meeting, declared the threat as non-specific," the official said.
However, he said, the standard operation procedure was adopted.
"We have strengthened the security. We have sanitised the airport. Though it appears to be a hoax call, we are not taking any chance," the official said.
Airport officials said flight operations were normal.