The Indian government blames a Pakistan-based Islamic militant group for the deadly attack on Parliament Thursday.

Five gunmen wielding grenades, AK-47 rifles and a human bomb stormed the colonial-style complex, killing seven people before being killed themselves.

Foreign Minister Jaswant Singh said Friday that India had issued a formal complaint to the Pakistan High Commission claiming it has evidence that the attack was the "handiwork" of the Pakistan-based Lashkar-e-Tayyaba militants.

Accusations over Thursday's violence have heightened tensions between Pakistan and India, both nuclear powers.

The gunmen drove through a Parliament gate with explosives, then fired the rifles in a gunbattle that unfolded over 35 minutes on the lawns and front steps of Parliament. One attacker blew himself up. No one has claimed responsibility for the attack. All of the attackers were killed.

Singh said the complaint, given to Pakistan High Commissioner Ashraf Jahangir Qazi by Indian Foreign Secretary Chokila Iyer, demanded that Pakistan halt the activities of Lashkar-e-Tayyaba and another Pakistan-based Islamic militant group, Jaish-e-Mohammed.

The formal demand also called for an arrest of leaders of the militant groups and freezing of their financial assets.

"I wish to emphasize that these demands are in accordance with necessary international obligations and commitments in countering terrorism," Singh said.

The two groups are among several fighting to separate Kashmir from India. Two-thirds of Kashmir is run by India, while the rest is controlled by India's western neighbor, rival Pakistan. Both claim the entire territory.

The Jaish-e-Mohammed group is accused of carrying out a suicide bombing attack against the Jammu-Kashmir state legislature on Oct. 1. That assault claimed 40 lives.

Yahya Mujahid, spokesman for the Lashkar-e-Tayyaba, said in Islamabad: "It's a pack of lies. The attack was sponsored by India itself. The whole drama was staged to malign Kashmir's Islamic groups and to involve Pakistan."

He said, "India wants to use the present international atmosphere against terrorism against Pakistan. No Kashmiri group is involved in attacks on civilians."

Singh would not reveal the evidence India claims to have against the militant organizations.

"There are obvious difficulties in revealing the evidence right now," he said. "The agencies of government have many means of obtaining intelligence."

He said India had consulted with the United States and other countries about the evidence.

India has long accused Pakistan of sponsoring and funding the Islamic militants who are fighting for independence in the disputed Himalayan province of Kashmir.

India and Pakistan have gone to war twice over the territory, which both countries claim in its entirety. India has been skeptical of Pakistan's new role as a key ally in the U.S.-led global war on terrorism.

"Pakistan has asserted that it is with the rest of the international community in combatting terrorism and that it does not promote terrorism," Singh said. "We expect that Pakistan will abide with what it says itself."

Asked whether India intended to take action against the militants on Pakistani territory, Singh said: "India has said what it has to say through the voice of the statement of the Cabinet."

On Thursday, the Cabinet issued a pledge to fight terrorism.

"We will liquidate the terrorists and their sponsors, wherever they are, whoever they are," the statement said.

The Associated Press contributed to this report.