"In the wake of the e-mail threat, we have called for additional force from other cities of the state. Vigilance has been stepped up and checking of vehicles intensified," City Police Commissioner Sudhir Sinha said.

"Assistance of Anti-terrorist Squad and crime branch is being taken," he said, adding "we are checking for sleeper modules from outside too".

Delhi police had received an e-mail, purportedly sent by the Indian Mujahideen, after the blast outside Delhi High Court, which spoke about the next target in a coded language, interpreted to be Ahmedabad.

"As the e-mail threatens of a blast that cannot be forgotten in "ten years", whether (the information is) correct or incorrect, we have taken all precautionary measures," Sinha said.

The schools and hospitals had been asked to step up the security and not to allow outsiders into the premises. If a stranger was to be allowed in, his/her baggage should be checked thoroughly, or left outside the premises, he said.

Earlier, following the email, Union Home Minister P Chidambaram stated "it could be cracked within a few minutes.

The numbers read as Ahmedabad".