Admitting that there was no credible intelligence input on the Mumbai attack, home minister P. Chidambaram today did not rule out any angle, including the possibility of an attempt to derail Indo-Pak talks, behind the blasts.

Expressing “deep regret” to the people of Mumbai over the incident, he said the probe will not start on any "pre-determined assumptions" and will cover every terror group that has the capacity to carry out such strikes in the country.

Mr Chidambaram said there was no intelligence failure on the part of Central and state agencies.

"There was no specific intelligence input on this...Whenever there is an intelligence, we share it with the states," he told a 70-minute press conference here.

"We are not ruling out any angle. We will probe (the involvement of) every terror group... The investigations into the attack will not start on pre-determined assumptions," he said.

He was speaking after a high-level meeting with Maharashtra chief minister Prithiviraj Chavan and senior ministers and officials to review the situation in the wake of the serial blasts that left 18 people dead, including a severed head that is yet to be idenitified, and 131 injured.

Union home ministry had officially stated in its first bulletin last night that the death toll was 21.

Asked whether the blasts were an attempt to derail the Indo-Pak talks later this month, Mr Chidambaram said that every angle will probed in the case.

"I do agree that the Indo-Pak talks will be held this month, in 10 days from now. We are not ruling out any angle. We will probe every angle," he said.

The home minister also said that India was living in the "most troubled neighbourhood" as Pakistan and Afghanistan are the "epicentres" of terrorism.

Giving details about investigations carried out since last night, Mr Chidambaram said ammonium nitrate, an explosive substance, was used in the IEDs, which had timer devices.

He ruled out the use of remote control to trigger the blasts in Zaveri Bazar, Opera House and Dadar areas in Mumbai.

In Dadar, he said, the explosive material was planted in a bus shelter, at Opera House the bomb was on the road that left a deep crater while in Zaveri Bazar it was kept in a motorcycle.

"No group has so far claimed responsibility for the blasts," Mr Chidambaram said, while making it clear they were not aimed at any particular community.

Terming the attack as a "coordinated strike", he said, "Whoever perpetrated this attack has worked in a very, very clandestine manner."

He said among the 131 injured, who were taken to 13 hospitals, 26 were discharged after treatment, 82 are in a stable condition while 23 people are in a serious condition. Of these, some are in critical state, he said.

To a question, the home minister said that the target is India's "unity, integrity and prosperity" and assured that "every foreigner in India is safe."

"If an incident like this happens, let me assure you it is not targeted against any foreigner or tourist visiting India. It has happened at some places on last occasions as some foreigners were present in hotels. Therefore, they lost their lives," he said.