ISLAMABAD, Pakistan - U.S. Senator John McCain says Pakistan understands it must take quick action against any terrorists connected to the Mumbai attacks that are living in the country.
McCain spoke after meeting with Pakistani leaders.
Indian authorities say the attackers were members of a banned Pakistani militant group that was set up by the country's intelligence agencies to battle Indian rule in the disputed Kashmir region.
The attacks have ratcheted up tensions between the nuclear-armed countries, which have fought three wars in the last 60 years.
Asked about the possibility that India may take military action if Pakistan doesn't react to its allegations, McCain said he believes Islamabad will co-operate with India.
He says it will act to avert any further deepening of the crisis.
"From our meetings we have had today we are encouraged that the government of Pakistan will show that co-operation in words and deed," he told reporters Saturday after meetings with Pakistan's prime minister and military chief.
McCain came to Pakistan with two other U.S. senators - Joseph Lieberman and Lindsey Graham - as part of a regional tour as members of the Senate Armed Services Committee.
They previously visited India.
The attacks have triggered an intense round of diplomacy to stop relations between the two countries deteriorating, something Washington fears will affect its campaign against al-Qaida in the region.
Earlier, the government denied reports that a man pretending to be India's foreign minister spoke to President Asif Ali Zardari over the phone during the Mumbai attacks.
Dawn newspaper reported the alleged hoax call Saturday, and said it prompted Pakistan to put its air force on high alert.
A security official later said a man pretending to be Foreign Minister Pranab Mukherjee had spoken to him in a "threatening manner."
But Information Minister Sherry Rehman said in a statement that the call "was placed from a verified official phone number of the Indian Ministry of External Affairs."
She did not explicitly say that the call was from Mukherjee, but two other government officials said it was him.
They spoke on condition of anonymity because of the sensitivity of the situation.
