The sleuths of the West Bengal Criminal Investigation Department have launched a massive operation to track down the owner of the SIM card that was recovered from the blast site in Hyderabad after Andhra Pradesh police traced it to Asansol in Burdwan district in West Bengal.

The SIM card was bought sometime in the second week of this month from Asansol. The calls had been made to Bangladesh and Pakistan, sources said here on Sunday. What has been worrying the Bengal CID is whether the notorious Huji (Harkat-ul-Jihad- Islami) Bilal alias Shahid Bilal who is suspected to be behind the Hyderabad blast, had a base in the state. Huji has a sprawling base in Bangladesh and for the Huji ultras, the easiest way to infiltrate into India is through the porous Indo-Bangla border in West Bengal.

The associates of Bilal might have used the Bengal corridor to travel to Mumbai and Andhra Pradesh, sources said. They are also not ruling out a Mumbai link to the Hyderabad blasts.

Also, a  high-level team headed by DIG-CID (Operations) Rajeev Kumar, is understood to have conducted some raids in the city