(A police sketch of one of the militants killed in Burdwan)

KOLKATA/BURDWAN: The Mamata Banerjee government on Monday came around to concede that last Thursday's accidental bomb blast in Burdwan involved al-Qaida linked Bangladeshi terrorist organization, Jamaat ul Mujahideen, even as it struggled to fend off pressure from political opponents to let National Investigation Agency (NIA) probe the explosions.A joint state task force, headed by the CID, said in a report to the state home department that a Bangladeshi terror outfit was behind the blast and that those killed and the accused are its cadre. The report came amid growing evidence of Jamaat-ul-Mujahideen's involvement in the explosions and indications that central agencies may have "nudged" the state government to revisit its earlier stand attributing the blasts to a battle between gangs of criminals aligned with two major political parties.The changed stance encouraged BJP and CPM to step up their criticism of the state government.Arguing that the state government cannot be trusted to conduct a fair probe, CPM's Amal Haldar sought the immediate removal of Burdwan SP, S M H Meerza, and a probe against him.BJP went a step further and demanded that the investigation be handed over to the NIA."The blast is an act of terror and it has implications on international and national security. The state should hand over the investigations to NIA. The Centre will put pressure on the state to hand over the investigation," BJP general secretary Siddharth Nath Singh told agencies. He said it is a matter of national security — an aspect which should not be neglected for narrow political interests of TMC.NIA Act does allow the Centre to suo motu hand over investigation into any "scheduled" offence to the agency, but the provision has not been invoked so far.This did not seem to deter the BJP which has expressed the apprehension that state agencies might cover up the case. "Why is the Trinamool Congress government not handing over the probe to NIA? The delay is raising serious questions of cover-up. BJP demands that investigation be handled by NIA and no other agency," Singh said.Alleging that links of a senior police officer in Burdwan with TMC were "very well known", Singh said he had been transferred by the Election Commission just before the 2014 Lok Sabha polls and chief minister Mamata Banerjee had promised to bring him back to the same position after the elections, which she did."Has the TMC regime used its favourite officer to destroy evidence and cover up the role of a section of TMC leaders in anti-national activities?" Singh asked.Both BJP and CPM have based their allegations on the alleged keenness of the state government to underplay the explosions during Durga Puja festivities despite overwhelming evidence that those could not have been the handiwork of ordinary criminals. Scores of bombs, hand grenades and gelatine sticks were recovered from the house which, it seems, functioned as the bomb-assembling unit for al-Qaida linked Bangladesh's terror outfit Jamaat-ul-Mujahideen.Besides, jehadi literature, including pamphlets carrying messages of solidarity with Islamic terrorists of Chechnya and other places, bomb-making manual and designs of rocket launcher were also found on the spot. The mobile phones of those killed were taken away by the sleuths.Sources in central agencies confirmed that the state police insisted on seeing the incident as the fallout of rivalry between groups aligned with TMC and CPM in the panchayat elections, and the normal pattern of members of political parties stockpiling explosives.