Indian police alleged Sunday that a suicide attack on the national Parliament was organized by two Pakistan-based militant groups at the direction of Pakistan's intelligence agency.

Pakistani government spokesman Anwar Mahmood rejected the allegation, repeating President Gen. Pervez Musharraf's statement Saturday that India has provided no proof of any Pakistani involvement. Musharraf also warned against Indian reprisals and put his army on high alert.

In Washington, Secretary of State Colin Powell urged India and Pakistan to work together against terrorism and avoid escalating tensions, saying the situation "has the potential of becoming very dangerous."

"What we don't want to do is see the rhetoric get so ratcheted up that the rhetoric is then followed by action which lets the whole situation go out of control," Powell said Sunday on NBC's Meet the Press.

On Saturday, India's leaders accused Pakistan of responsibility for the carnage in the Parliament and warned that the attack demands a strong response. Musharraf said India had no proof the attackers operated from his country or were supported by it.

Announcing the results of an investigation Sunday, New Delhi police commissioner Ajay Raj Sharma named five Pakistanis he said carried out the suicide raid, which killed 13 people including the attackers.

Sharma said the attack was planned by leaders of Jaish-e-Mohammad and Lashkar-e-Tayyaba, two Islamic militant groups fighting to separate the mostly Muslim region of Kashmir from India, and accused Pakistan's Inter Services Intelligence, or ISI, of involvement.

Masood Azhar, a leader of Jaish-e-Mohammad, and Zaki-ur Rehman of Lashkar-e-Tayyaba "have both planned a combined operation on directions from Pakistan's ISI," Sharma said. He said the conclusions were based on statements from four people who were arrested and confessed involvement.

"The ISI connection is very clear," he said. "These people have not said that Pakistan was in the know, but the things that come to our notice show that the ISI was connected to it [the attack], and if the ISI is involved, Pakistan ought to know about it."

No one has claimed responsibility for the attack, and Jaish-e-Mohammad and Lashkar-e-Tayyaba have denied involvement.

Sharma said Mohammad Afzal, who he said admitted to being a Jaish-e-Mohammad member after he was arrested Saturday on suspicion of supervising the attack, was trained by the ISI.

Indian police said an Arabic lecturer they detained told investigators that Afzal and Shaukat Hussain, both Muslims from Kashmir, coordinated the attack and provided guns, grenades and explosives. Sharma said Afzal and Hussain fled New Delhi and were arrested Saturday in Kashmir.

Sharma said the attackers were led by a man identified as Mohammed. Kashmir's police chief said Sunday that in 1999, Mohammed was among the hijackers of the Indian plane whose passengers were freed in exchange for the release of Azhar and other militants from prison in India.

The parliament attack has sharpened tension between India and Pakistan, nuclear rivals that have fought three wars in half a century.

India accuses Pakistan of arming and training Islamic militants who have fought a bloody separatist insurrection since 1989 in the Indian-ruled part of Kashmir. Indian officials have said there are links between some of the Kashmir guerrillas and Usama bin Laden.

Pakistan, which calls the insurgents freedom fighters but denies it arms or trains them, is under pressure to rein in militants as an ally in the U.S.-led campaign against bin Laden, the main suspect in the Sept. 11 terror attacks, and his Al Qaeda network.

Musharraf allied Pakistan with the United States this fall in the successful fight to oust bin Laden's Taliban protecters, who took power in Afghanistan five years ago with support from Pakistan and factions in the ISI.

The U.S. pledge to root out terrorism has put a spotlight on the militants in Kashmir, and India has been urging the United States to see its struggle against the separatists there as part of the worldwide fight against terror.

India has called on Pakistan to shut down Jaish-e-Mohammad and Lashkar-e-Tayyaba, arrest their leaders and freeze their funds.

Musharraf promised Saturday to take action against anybody whose involvement in the Parliament attack is proven.

Indian Prime Minister Atal Bihari Vajpayee said Saturday that Pakistan was "inspiring" terrorists and warned "the sponsors are destined to doom."

Powell defended the Indian government's "legitimate right of self-defense" but called for caution, adding that "if, in the exercise of that right of self-defense, we have states going after each other, we could create ... a situation that could spiral out of control."