Uttar Pradesh Chief Minister Mulayam Singh Yadav on Friday did not rule out the involvement of terrorist groups in Thursday's blast in the New Delhi-bound Shramjeevi Express, which left 12 dead and 62 injured.

"It was apparent that some terrorist groups were responsible for carrying out the blast in the general compartment of the train," Yadav told reporters in Varanasi in a hospital at the Benaras Hindu University premises, after enquiring into the condition of the injured passengers admitted there.

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The involvement of the particular terrorist group in the train blast would become clear after the ongoing probe into the matter is completed, he said.

Describing the blast as a 'heinous crime', Yadav said the subversive designs of the terrorist outfits would not be allowed to succeed as preventive measures were being taken by the Centre and state governments to foil such attempts to destabilise the country.

He also announced an ex-gratia payment of Rs 1 lakh to the family members of the victims of the blast and handed over a cheque of Rs 50,000 each to the injured passengers.