A top source in the force said the e-mail was sent to the CP's official mail address at around 2.30 PM today spurring the police to tighten security around the iconic building, which is under renovation.
Kolkata Police Joint Commissioner of Police (Crime) Pallab Kanti Ghosh said e-mail was written in broken English and asked Kolkata Police to 'Check for bomb in Writers' Building'.
On investigation, it was found the threat was fake and the mail was sent from a fake address, he said.
Immediately after receiving the mail, security around Writers' Buildings was beefed up and senior Kolkata Police officers along with the bomb squad personnel and sniffer dog squad rushed there. It was vacated as part of security measure.
Besides regular policemen, Kolkata Police personnel in plains clothes would be posted at the heritage premises tonight, police said.