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.
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 officialy stated in its first bulletin last night that the death toll was 21.