Mumbai investigators comb triple bombing site for clues

At a news conference in Mumbai, India’s top security official, Home Minister Palaniappan Chidambaram, would not speculate about who might have carried out the bombings. “We are not pointing a finger at this stage,’’ he said. “We have to look at every possible hostile group.’’

Intelligence officials had picked up no warnings that an attack was imminent, Chidambaram said.

“Whoever has perpetrated this attack has worked in a very, very clandestine manner,’’ he said.

The home secretary, R.K. Singh, said that ammonium nitrate, a fertilizer component, had been used in the bombs, and that the early evidence pointed to the use of timers rather than remote triggers as the detonators. The explosions took place within minutes of one another in crowded areas of the city.

“They were not crude bombs but sophisticated devices,’’ Singh said in New Delhi. “Only somebody who has training can assemble those devices.’’

The chief of Mumbai’s antiterrorism squad, Rakesh Maria, said heavy rain was hampering forensics investigators.

A senior US law enforcement official said early indications pointed to India-based militants, not to Lashkar-e-Taiba, a militant group in Pakistan that is suspected of being behind the 2008 assault on Mumbai. But the official, who spoke on the condition of anonymity because of the delicacy of the matter, cautioned that the investigation was still in its early stages and that it was premature to make any firm conclusions. The police described the bombs as improvised explosive devices.

Determining whether the attacks were carried out by a domestic group such as India’s mujahedeen or a foreign group such as Lashkar-e-Taiba was essential to understand what the political impact might be, analysts said.

India and Pakistan have only recently restarted formal talks that had been suspended in the aftermath of the 2008 attacks, gingerly discussing issues such as the status of the disputed region of Kashmir. Pakistan’s foreign minister is scheduled to visit India this month, and a Foreign Ministry spokesman in India said the visit would go ahead as planned.