NEW DELHI, Jan 6(TOI): The National Investigation Agency probing the blast on Samjhauta Express in February 2007 looks set to book militant Hindutva leader Aseemanand. It has identified Aseemanand as the key plotter of the attack that killed 68 people, majority of them Pakistani citizens returning home after visiting their kin in India.

Sources in the agency, which was brought in after investigations by Haryana Police reached a dead-end, told TOI that Aseemanand planned the blast to avenge the series of terror attacks by Islamist terror groups.

"The role of Hindu extremists behind the blast has become clear. The probe agency found that Aseemanand was one of the plotters. The group had done it under their 'Bomb-for-Bomb' plan which was hatched in the Dangs district of Gujarat," said sources in the NIA.

Haryana police had found similarities in the explosives used in the Samjhauta blast and the explosion at Hyderabad's Mecca Masjid, another attack suspected to have been carried out by Aseemanand and his comrades under the 'Bomb-for-Bomb' plan.

But the Haryana cops could not connect the dots. The picture was further complicated when the US named a Pakistani terrorist, Asif Kasmani, suspected to be a go-between Lashkar and al-Qaida, as the main suspect in the Samajhauta blast.

NIA's probe into the cases of saffron terror has gathered momentum after the arrest of Aseemanand who is believed to have inspired Abhinav Bharat members to retaliate against Islamist terror.

NIA's investigation into the Samjhauta train attack may give Pakistan a handle to embarrass India. Officials are wary of the possibility of Islamabad asking for Aseemanand's custody once he is charge-sheeted. But the government has decided to press ahead with the probe, said an official.