New Delhi  - Three days after serial blasts left 24 dead in the Indian capital New Dehli, President Pratibha Patil on Tuesday expressed serious concern over the emerging "metro terrorism" in the country.

Addressing a conference of state governors in New Delhi, Patil said the federal and regional governments would have to deal firmly with those who "followed the path and culture of guns."

India has seen a series of terrorist bomb attacks in urban centres over the past few years. In 2008 alone, there have been blasts in Delhi, Ahmedabad in the western Gujarat state, Bangalore in southern Karnataka and Jaipur in northern Rajasthan.

The two-day conference of governors, which is being attended by Prime Minister Manmohan Singh and Home Minister Shivraj Patil, has been called to take stock of the internal security situation in India in context of the bomb attacks, rising violence by Maoist rebels and the insurgency in Kashmir and the north-eastern states.

Describing terrorism, left-wing extremism and insurgency as the big challenges before the country, Patil said: "Outfits with varying goals have been waging a long and enduring war against the state with some forming a mutually supportive grid in this proxy warfare."

Without directly referring to neighbouring Pakistan, Patil said: "Intervention by trans-border elements also poses a threat to our security and integrity."

Patil's comments came as citizens of in the capital grappled with the aftermath of the blasts with several families holding funerals for more than one relative.

A 25-year-old man succumbed to his injuries in a hospital Tuesday, taking the death toll to 24 in the series of five explosions which rocked crowded New Dehli markets on Saturday. More than 100 people were injured.

A group calling itself the Indian Mujahideen has claimed responsibility for the bombings. A spokesman for the Delhi Police said sketches of three suspected bombers created on basis of witness accounts would be released soon.

A search was also on for Mumbai-based software professional Abdul Subhan Qureshi alias Taquir, who the police suspect of being the architect of the serial blasts, IANS news agency reported.

Taquir is believed to have sent emails claiming the Indian Mujahideen's responsibility for the blasts in Ahmedabad and New Delhi.

Meanwhile, a reform panel submitted a report Tuesday recommending comprehensive anti-terror legislation and the establishment of a federal agency to investigate terrorist acts.

The Administrative Reforms Commission said people accused of offences related to national security should not be released on bail and recommended setting up special fast-track courts for trying terrorism-related cases. (dpa)