India demanded that Pakistan hand over several terrorist suspects as the government faced mounting criticism on Tuesday over intelligence failures in the Mumbai attacks that left 188 dead.
But Pakistan's prime minister said his government wanted proof of India's allegation that all the attackers were Pakistanis, as tensions rose between the two nuclear-armed neighbours over the siege of India's financial capital.
CNN and another US network reported that the United States had warned India in October that hotels and business centres in Mumbai would be targeted by attackers coming from the sea, as happened in last week's dramatic assault.
One US intelligence official had even named the Taj Mahal hotel, one of 10 sites hit in the 60-hour siege by gunmen, as a specific target, ABC television said.
It said Indian intelligence officials intercepted a phone call on November 18 to an address in Pakistan used by the head of the militant Lashkar-e-Taiba, revealing a possible attack from the sea.
About 10 gunmen landed in rubber dinghies in Mumbai on Wednesday and wreaked havoc with automatic weapons and hand grenades, in an assault that killed 188 and injured more than 300.
India's security and intelligence agencies have come under intense criticism over their handling of the incident, including allegations that not enough was done to prevent such an attack.
"Such comprehensive failure was held up to the world's view during 60 hours of unprecedented trauma, featuring 10 heavily armed terrorists who sailed into Mumbai from Pakistan and penetrated Indian defences as if it was child's play," The Hindu newspaper said on Tuesday.
Pakistan formally banned Lashkar-e-Taiba, which has fought Indian rule in divided Kashmir and was blamed for the 2001 attack on the Indian parliament which almost led the two nations to war, in 2002.
But Indian officials allege that Pakistan has not fully enforced that ban, allowing the group to continue operating, and India says all the dead gunmen and the lone man arrested in the attack were all from Pakistan.
Diplomatic sources said India's ambassador to Islamabad met senior Pakistan officials on Monday and demanded the handover of several militant suspects, including Lashkar-e-Taiba's leader, Hafeez Sayeed.
Pakistan Prime Minister Yousuf Raza Gilani meanwhile told CNN that his government wanted proof of allegations that his country's nationals were involved.
"They have given us (the names of) some of the organisations ... but that is not evidence. If they will give us evidence we are commmitted that we will extend full cooperation," Gilani said.
"Let the proof come, then we will give our point of view."
He also played down reports that Pakistan could move troops away from the fight against Al-Qaeda and Taliban militants in the country's northern tribal areas to reinforce security on its eastern border with India.
"Pakistan will act very responsibly," the prime minister said. "We have talked to all our friends that they will use their good offices to defuse the situation."
Questions about whether India ignored US intelligence warnings and if Pakistan would divert troops from the Afghan border will likely come up in discussions with US Secretary of State Condoleezza Rice, who arrives on Wednesday.
She is due to meet with Indian officials though there has been no announcement if she will also visit Pakistan, a close ally in the US-led "war on terror" since the September 11 attacks on the United States in 2001.
India and Pakistan have fought three wars and nearly came to a fourth after the 2001 parliament attack, and the United States has urged both nations to remain calm in the wake of the latest bloodshed.
"In some ways that whole region is like a forest that hasn't had rain in many months and one spark could cause a big, roaring fire. That's what we're trying to avoid," White House spokeswoman Dana Perino said on Monday.
"Obviously we want to help reduce tensions wherever possible," she said.