New Delhi: Central Intelligence agencies have found the role of suspected over ground workers of Khalistani extremists group associated with Pakistan-based terrorist, in a blast reported at Punjab Police's intelligence headquarter building in Mohali on Monday.

A police official said that during the investigation they found the mobile location of a suspect associated with Pakistan-based terrorist Harvinder Singh Rinda near the blast site.

"We have scanned hundreds of mobile phone locations after accessing dump data of all mobile towers falling in the radius of blast site and found a number of few suspects," he said.

He added that one of the numbers allegedly belong to an over ground worker associated with Rinda. Teams have been formed to catch the suspect to get more information in the case.

"It is also suspected that the Rocket-propelled Grenade (RPG) was smuggled into India from Pakistan border because Rinda was allegedly involved in smuggling of arms and ammunition from the cross border," he said.

On Sunday, Punjab Police had recovered an explosive device packed with around 1.5 kg of RDX and arrested two men in a village in Tarn Taran district. The explosives were allegedly smuggled for terror activities.

However, Central intelligence agencies have also swung into action to get breakthroughs in the case.

A senior official associated with a Central intelligence agency said that it is suspected that a rocket-propelled grenade (RPG) was used in the attack and it is an unusual thing. In the past, grenade attacks have happened but the use of RPGs is worrying for everyone.

On May 9, Himachal Pradesh Director General of Police issued an alert in the state in the view of Khalistani elements in neighbouring states and the installing banners and graffiti of Khalistan on the outer boundary of Vidhan Sabha.

He added that Punjab Police has also issued an alert after the blast in Mohali. But instead of written communication, they have verbally communicated to all Police officers to be on alert.

According to Mohali police, a minor explosion was reported at the Punjab Police Intelligence Headquarters in sector 77 at around 7.45 pm. No damage has been reported. Senior officers rushed to the spot and an investigation is being done. Forensic teams have been called.

On May 8, two persons were held in the Taran Taran district of Punjab. Police recovered an Improvised Explosive Device (IED) equipped with RDX packed in a metallic box weighing over 2.5 kg from the two arrested.

On May 5, four terror suspects were arrested in Karnal, Haryana. Police recovered three IEDs weighing 2.5 kg each from their possession.