Deccan Mujahideen email threatens Delhi

The Intelligence Bureau has also sounded a fresh alert to Delhi Police asking them to step up security at vital installations in the capital after an email, which police sources said was signed by the "Deccan Mujahideen", warned of a repeat of the Mumbai terror attack at Indira Gandhi International Airport and the three major railway stations.

Acting on the three-wheeler threat, police are conducting random checks on autos, particularly around the airport. During the last serial blasts in Delhi, a bomb had gone off in an auto at Ghaffar Market in Karol Bagh. At that time too there had been intelligence alerts on the possibility of key installations in Delhi coming under threat from autos.

Experts say, since three-wheelers run on CNG, an 'auto bomb' is likely to cause more damage than an explosion in a petrol or diesel vehicle.

"The information said that explosives in an auto were likely to be planted and set off in a crowded area. After that, the airport has been checking on idle autos and those which enter the premises without passengers. The threat still holds and checking has been intensified," said a government source.

Police sources do not rule out the possibility of the September 13 Ghaffar Market blast having been a "test case" for a bigger strike.