Authorities in New Delhi have received an anonymous e-mail threatening to blow up the . This has prompted them to step up security by deploying additional forces inside and outside, said an official.

The information about the e-mail was passed on to higher officials of the CISF, which is handling security at the Indira Gandhi International Airport (IGIA).

The airport has been on high alert since terrorists struck Mumbai on Wednesday night.

"We have taken adequate precautions after receiving information about an email threatening to blow up the airport. There is nothing to panic. We are leaving nothing to chance. Adequate steps have been taken," a senior CISF official said.

The security establishment has also asked CISF to coordinate with Delhi Police to provide security to the 'city side' of the airport, which is outside the terminal building.

Fearing attack on aircraft, Delhi Police have already prohibited assembling of people or parking of vehicles at a 500-metre stretch on the NH-8 near the airport.