The United States Monday ramped up pressure on Pakistan to crack down on militants after the deadly Mumbai attacks but denied reports it set a 48-hour deadline for action. US Secretary of State Condoleezza Rice said Pakistan must act quickly to help India prevent follow-on attacks, adding there was no doubt Pakistani soil was used by "non-state actors." Her comments came as tension simmers between the two nuclear-armed South Asian neighbours in the aftermath of the violence, which has enraged public opinion in India and threatened a slow-moving peace process. Suspicion over the Mumbai carnage, which left 172 dead, including nine gunmen, has fallen on Pakistan-based Lashkar-e-Taiba, a group that has fought Indian rule in Kashmir and was blamed for a 2001 attack on the New Delhi parliament. India says all 10 gunmen involved in the assault came from Pakistan, and has handed Islamabad a list of 20 terror suspects, with demands for their arrest and extradition. Ties were strained further Sunday when India's foreign minister said Pakistani reports about a hoax call made in his name during the Mumbai siege were an attempt to divert blame for the attacks. Speaking on US television, Rice said she stressed during her recent visit to Pakistan how important it was for Islamabad to cooperate fully and promptly with India. "The important thing is that Pakistan act and that these people are brought to justice and that any information that they may have is put to use in making sure follow-on attacks don't happen," she said. Rice said there was no strong evidence Pakistani officials had a role in the November 26 attacks but added they had "responsibility" to take action. "I think there is no doubt that Pakistani territory was used by probably non-state actors. I don't think that there is compelling evidence of involvement of Pakistani officials," Rice said. "But I do think that Pakistan has a responsibility to act," she said. Rice also echoed remarks from Pakistan's foreign office denying Islamabad had agreed to a 48-hour timetable to take action against Pakistanis accused of involvement in the attacks. Separately, US president-elect Barack Obama called for a grand new approach to fighting terror in South Asia that would include pressing India and Pakistan to heal their divide over Kashmir. Meanwhile, India's foreign minister Pranab Mukherjee on Sunday denied he had made a telephone call to Pakistani President Asif Ali Zardari threatening military action. The apparent hoax call put Pakistan on high alert of a military strike by India while militants were still battling security forces in Mumbai. The caller told Zardari that India would take military action if Islamabad did not hand over those behind the attacks, Pakistani newspapers reported on Saturday.