A sleeper cell of the Indian Mujahideen (IM), a home-grown Islamist terrorist group, is strongly suspected to be behind Saturday's Pune bombing that has come days after the arrest of one of its top operatives, highly placed sources said.
The attack - on a "soft target" like the German Bakery - is a "copycat strike" of what the group had used in carrying out bombings earlier in Bangalore, Ahmedabad and New Delhi in 2008, the sources told IANS.
Intelligence agencies that collected material evidence from the blast site at the German Bakery and also questioned afresh the terror outfit's arrested operatives say the needle of suspicion points towards the Indian Mujahideen.
The materials used, RDX and ammonium nitrate, and the pattern of the blast point towards the IM's modus operandi, the sources told IANS on conditon of anonymity, as they are not supposed to speak to the media during the course of the investigation.
The IM had owned up to a series of blasts in various cities across the country in 2008. It is believed to be a shadow organisation of the banned Students Islamic Movement of India (SIMI) and the Pakistan-based Lashkar-e-Taiba.
"Explosives like RDX and ammonium nitrate were used to carry out the Pune bomb blast. It is almost a copycat strike like what the IM had used in carrying out blasts in 2008 in Bangalore, Ahmedabad and Delhi," an investigator told IANS.
"We also feel that this attack could be payback for the arrest of alleged Indian Mujahideen operative Shahzad Ahmed who was recently nabbed in connection with the 2008 Delhi serial blasts from his village in Azamgarh (Uttar Pradesh)."
The blast at Pune's German Bakery Saturday evening killed nine people, including two foreign nationals, and injured 60. The explosive was hidden in a backpack and went off when a waiter attempted to open it.
"It was an insidious and hidden attack, the way Indian Mujahideen operatives did in 2008 and not the one we saw in Mumbai (26/11)," the official said.
"These are all trademarks (of the IM) and we are working on some leads that we have got. We have already got some good information," he said.
"We are strongly looking at the IM angle. Though David Headley, the suspected LeT operative (now in a US prison), carried out an extensive recce in India, we do not think this is a work of the Pakistan-based militant group," a senior security official told IANS.
"They (LeT) would have normally struck at a market place or a cinema hall rather than a soft target like the German Bakery," the official said.
Sources in the home ministry said Home Minister P Chidambaram has been "extremely upset and bristling with anger" over the attacks "considering that the Multi Agency Centre (MAC) and its subsidiary have been working so well all this while since the 26/11 attacks".
Security agencies have also launched a massive manhunt to arrest the IM's Pune-based operative Moshin Chaudhary, who took over as head of the terror organisation following the arrest of some of key leaders of the outfit. The Maharashtra Anti-Terrorist Squad (ATS) believes that Chaudhary was instrumental in setting up several modules of the outfit in India, including one in Pune.
He also played a key role in operation BAD -- a code name for terror attacks in Bangalore Ahmedabad and Delhi in 2008.
Important members of the IM arrested following the 2008 blasts are Safdar Nagori, the main architect of the Indian Mujahideen, Mufti Abu Bashir, Qayamuddin Kapadia, Mansoor Peerbhoy and Sajid Mansuri. Chaudhary had introduced software engineer Mansoor Pheerbhoy to the IM. He built up the tech cell of the outfit.
The Delhi Police, currently interrogating Shahzad who was nabbed February 2, have also extended their manhunt to arrest Chaudhary and help the Maharashtra ATS crack the Pune blast case.
Sources also said that the government was not averse to seeking foreign help on this attack which has taken place 14 months after the Mumbai terror strike when 10 LeT militants sneaked into the country's financial capital from the sea and laid siege to the metropolis for three days, killing 166 people, including foreigners.