In her first testimony to Congress since her confirmation as the US chief diplomat in January, Clinton said Pakistan, poses a mortal threat to the security and safety of the US and the world.

She asked Pakistani government officials as well as Pakistanis at home and abroad, including in the United States, to "speak out forcefully against a policy (Swat peace accord) that is ceding more and more territory to the insurgents".

"I think that we cannot underscore the seriousness of the existential threat posed to the state of Pakistan by the continuing advances now within hours of Islamabad that are being made by a loosely confederated group of terrorists and others who are seeking the overthrow of the Pakistani state, which is, as we all know, a nuclear-armed state," Clinton asserted.

Briefing the House Foreign Affairs Committee about the foreign policy initiatives of the Obama Administration, she expressed concern that this seriousness was not visible among the Pak leadership.

"I don't hear that kind of outrage or concern coming from enough people that would reverberate back within the highest echelons of the civilian and military leadership of Pakistan," US Secretary of State said.

She also said that in Afghanistan and Pakistan, President Barack Obama had outlined a strategy to disrupt, dismantle and defeat Al Qaida, and to prevent their safe return to havens in Afghanistan or Pakistan.

"We combined our strategic review with intensive diplomacy, and nations from around the world are joining our efforts. More than 80 countries and organisations participated in the international conference in the Hague, and a donors' conference just concluded in Tokyo raised over USD 5 billion," Clinton said referring to Obama's AfPAk policy.

Meanwhile, expressing concern over the recent developments in Pakistan, Chairman of the House Foreign Affairs Committee Howard Berman on Thursday told the Secretary of State that America can't allow a free run for the Taliban and Al Qaeda in the tribal regions of Pakistan and let them rapidly expand their territorial control.

The US has an enormous stake in the stability and security of Pakistan, Berman said at the Congressional hearing.

"We can't allow Al Qaida or any other terrorist group that threatens our national security to operate with impunity in the tribal regions, nor can we permit the Pakistani state and its nuclear arsenal to be taken over by the Taliban or any other radical groups, or otherwise be destabilized in a manner that could lead to renewed conflict with India," Berman added.

Berman who was recently in India and Pakistan as part of a Congressional delegation said "It is very alarming that we're now hearing predictions from a number of leading experts that Pakistan could collapse in as little as six months."

Deeply concerned about the rapidly deteriorating security situation in Pakistan, Berman said "In recent weeks, extremists based in the western border regions have turned their guns on the Pakistani state, launching dramatic suicide attacks in the population centres of Islamabad and Lahore."

Equally troubling, the Pakistani government has cut a deal with the extremists that overran the Swat Valley, the latest in a string of failed agreements that has only emboldened the radicals, he said.

"To make matters worse, the Pakistani Supreme Court just ordered the release of Maulana Abdul Aziz, the radical Red Mosque cleric who has renewed his call to kill westerners and place all of Pakistan under a rigid and intolerant form of Islamic law," he said.

Berman, who had recently introduced a bill in the House of Representatives for USD 1.5 billion a year aid to Pakistan, with conditions attached, said he strongly support your conclusion that strengthening the civilian democratic government of Pakistan should be an essential part of US's overall efforts.