Principal Secretary of Home, Alok Sinha told reporters that bomb disposal squads are on the lookout for any possible explosives at the Charbagh railway station where security was beefed up. He said the divisional manager of north-eastern railway received the letter claiming that explosives have been planted at Charbagh station on Sunday.

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"Security at all railway stations including Charbagh was tightened as a precautionary measure though the letter appears to be bogus and meant to create panic," he said.

Sinha said bomb disposal squads had been scouring the Charbagh station premises since 2 pm on Sunday but no explosives had been recovered till evening.

He said that the Special Task Force was entrusted with the responsibility of finding the origin of the letter written on a plain paper and mentioned the name of one Mohammad Ahmed who claimed to be the 'area commander' of al Qaeda.