Two days after the Delhi high court blast, Home Minister P Chidambaram Friday said there were "promising" but not "very conclusive leads" in the case and agencies of foreign countries had also been roped in.
He did not rule out cross-border connection, saying, "At this moment, every organisation is suspect" and he was "keeping fingers crossed till we have evidence".
Addressing a press conference in New Delhi, Chidambaram said a "strong" team of investigators, comprising specialised National Investigative Agency and Delhi Police, are pursuing the blast case vigorously.
A person, suspected of sending e-mail immediately after the blast, has been taken in for questioning in Kishtwar in Jammu and Kashmir.
"We have to wait for that report to come," he said. "As far as investigations are concerned, there are promising leads but I can't yet call them very conclusive leads," he said.
Chidambaram said all information and leads are being taken seriously and being pursued by the investigators round-the-clock.
"I wish to emphasise round-the-clock as we are seeking help from other agencies from around the world too. Therefore, these leads are pursued round-the-clock by very strong team that has been constituted by NIA and Delhi Police. All other agencies are helping," he said.
Referring to the first email which claimed responsibility for the blast, the Home Minister said it was sent from a cyber cafe in Kishtwar and that has been located.
"The person, whom we were looking for as a suspect, who sent the email, has been located and has been taken into custody for interrogation. We have to wait for that report to come," he said.
Chidambaram said subsequently two more emails were received, the last one today. "These were not dismissed though the third email appears to be very amateurish email. It could be cracked within a few minutes. The numbers read as Ahmedabad... So the email senders are hinting that the strike will be in Ahmedabad," he said.
Chidambaram said since it was a very simple code, very amateurish code, he was not very sure whether it was sent by a serious person.
"Nevertheless, we are taking it seriously and Gujarat government has been alerted," he said.
He said a detailed advisory has been sent to states reiterating earlier advisory and asking them to enhance vigil against similar terrorist attacks particularly in metropolitan areas and in big towns.
Owners and managements of such institutes, which usually attract large public congregation, have been advised to ensure strict access control and security related surveillance in respect of suspicious persons and objects, he said.
Chidambaram said security arrangements in Delhi are being reviewed and instructed to use optimum resources available and ensure synergy between all agencies in emergency response.
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