But again, the Delhi Police have admitted that there has been ``some kind of activity'' in the Amritsar-Ambala-Panipat-Delhi belt over the past three months. A large quantity of explosives, including RDX, has been seized from these areas and several explosions have occurred during this period. Another senior official adds that investigators are also exploring the possibility of a connection between today's explosion and the tension along the Line of Control in the Drass Kargil. ``It is also possible that someone is taking advantage of the situation there to create panic here,'' he says.

For the time being, nevertheless, investigators are concentrating on the ISI, usually suspect number one in any bomb blast. One of the reasons, they say, is that it is more or less established that the ISI had funded and planned the series of explosions which rocked Delhi in 1997 and early 1998.

In February 1998, the crime branch claimed it had cracked the cases after arresting 13 men. One of them, Kamran, they had said, had designed the crude bombs and triggered off most of the blasts. The crime branch had also reportedly identified the mastermind behind the blasts as Abdul Karim Tunda, now believed to have been killed in Bangladesh.

While Kamran and his associates are still in jail, the police are yet to trace those responsible for the three bomb blasts which rocked Delhi after Kamran's arrest. Neither have they made any headway in the case of an RDX explosion inside a train in Holambi Kalan, near Narela, on April 16, which killed two persons and injured three more.