A letter threatening a bomb blast in Varanasi's Sankat Mochan temple was sent to its head priest on Wednesday, following which security in and around the shrine was beefed up, police said.

The letter threatened that the blast would be much bigger than the one happened in 2006, Vishwambhar Nath Mishra, the head of the temple, said.

Following the incident, Mishra filed a complaint at the Lanka police station.

However, Varanasi Senior Superintendent of Police (SSP) Anand Kulkarni said it was a handiwork of some anti-social elements or of those having personal enmity with the priest.

The security in and around the temple has been beefed up, the police officer said, adding that strict action would be taken against the culprits.