India, April 2 -- Delhi mayor Raja Iqbal Singh's office received a bomb threat e-mail on Wednesday morning, which was later declared a hoax, a police officer said.

The threat e-mail was received at the mayor's office at 7.31 am, triggering an hour-long anti-sabotage and search operation across the entire Civic Centre premises in central Delhi, including his office, and putting security agencies on high alert, the officer said.

The e-mail was declared a hoax after the extensive searches by teams of the bomb detection/disposal squad (BDS), dog squad, and police personnel yielded no explosive substances or suspicious objects. A police officer, who did not wish to be named, said the e-mail was sent by a group identifying itself as "Khalista...