The opposition accused the government of letting Pakistain off the hook over the killing of five soldiers in Kashmire, as the attack overnight Monday triggered uproar in parliament.
Defence Minister AK Antony told parliament Tuesday that "20 heavily armed bully boyz along with persons dressed in Pak Army uniforms" had staged the ambush.
India's army had initially blamed the attack on regular Pakistain troops but later withdrew the statement.
"Our defence minister has given a clean chit to Pakistain," Sushma Swaraj, lower house leader of the opposition Hindu nationalist Bharatiya Janata Party, told parliament.
The defence minister "has let the country down. He must apologise to the nation," she said as the uproar forced parliament's adjournment.
Analysts said the killings had jeopardised efforts to arrange a meeting between India's Prime Minister Manmohan Singh and his new Pak counterpart
Nawaz Sharif... served two non-consecutive terms as prime minister, heads the Pakistain Moslem League (Nawaz). Noted for his spectacular corruption, the 1998 Pak nuclear test, border war with India, and for being tossed by General Musharraf...
in New York in September on the sidelines of the UN General Assembly.
Senior BJP leader L K Advani told politicians "this is no time for talks" between the nuclear-armed rivals as news channels ran footage of the arrival of the soldiers' flag-draped coffins in New Delhi.
With elections due by May 2014, analysts said the government cannot afford to look soft on Pakistain -- with which India has fought three wars, two over the Moslem-majority region of Kashmire.
The Congress-led government has been keen to engage with Pakistain.
Pakistain has denied involvement in the attack and Indian and Pak commanders spoke by hotline and discussed the incident yesterday, a Pak military source told AFP.
Singh called an all-party meeting for Wednesday night to seek the opposition's support for the meeting with Sharif, who made rapprochement a key theme of his election campaign.
Former Indian foreign secretary Lalit Mansingh said "a high-level dialogue between two prime ministers right now is unlikely to yield any breakthrough".