Indian police are linking Pakistan's main intelligence agency to the suicide attack last week on India's parliament. Pakistan denies involvement, but the latest comments are likely to worsen tensions between the two countries.
Delhi's Police Commissioner Ajay Raj Sharma told reporters the five gunmen who attacked India's Parliament were Pakistani citizens.
He says interrogation of four arrested suspects has revealed the daring attack, in which 13-people died, was a joint operation by two Pakistan-based militant groups: the Lakshar-e-Taiba and the Jaish-e-Mohammad.
He says Pakistan's Inter Services Intelligence (ISI) had been aware of the plot to attack parliament.
According to Mr. Sharma, the arrested men did not say that Pakistan knew about the attack, but "things which have come to our notice clearly show that the ISI was connected". He named two Pakistani militants as leaders of the plot.
"Under pressure of Pakistan's ISI, Masood Azhar and Zakkeer ul Rehman of [Lakshar-e-Taiba (LET)] have both combined, and on directions of Pak ISI a fidayeen [suicide] attack should be undertaken in Delhi and LET would provide all necessary support," he said.
The Delhi police says the four men who have been arrested provided logistical support to the gunmen and say they were trained by Pakistan's ISI.
Pakistan's government has denied involvement, and says it will punish anyone responsible if India can prove the attack was carried out from Pakistan. New Delhi has asked Islamabad to arrest the leaders and freeze the assets of the Lakshar-e-Taiba and the Jaish-e Mohammad groups.
Meanwhile, rhetoric against Pakistan is becoming sharper in New Delhi. Indian Prime Minister Atal Bihari Vajpayee said on Saturday that India cannot tolerate such attacks. Several legislators have demanded that Indian security forces should smash what New Delhi says are militant training camps in Pakistani Kashmir. Defense Minster George Fernandes has urged a "tough response."
Pakistan has reacted to the sharp rhetoric by warning that it is ready to retaliate if India takes action against the country.
India accuses Pakistan of training and arming Islamic guerrillas waging an armed insurgency in Indian Kashmir. Pakistan denies the charge.