The Rajiv Gandhi International (RGIA) Airport here received a bomb threat e-mail on Friday, prompting authorities to step up security.
The mail warned that there were "sleeper cells" and the "airport" would explode, following which searches were carried out and nothing suspicious was found, police said.
All precautions have been taken and security has been enhanced, they said.
"There was no specific mention (about planting bombs) and it was a general threat. We are on alert and taking extra precautions. Checking was done and so far nothing suspicious was found," he said in response to a query if they have declared the email a hoax.
A case was being registered. Further investigations were on.