WASHINGTON - Pakistan's government has abdicated to the Taliban in agreeing to impose Islamic law in the Swat valley and the country now poses a mortal threat to the world, U.S. Secretary of State Hillary Clinton said on Wednesday.

Surging violence across Pakistan and the spread of Taliban influence through its northwest are reviving concerns about the stability of the nuclear-armed country, an important U.S. ally vital to efforts to stabilize neighboring Afghanistan.

U.S. President Barack Obama, who on March 27 unveiled a new strategy that seeks to crush al Qaeda and Taliban militants in Afghanistan and those operating from across the border in Pakistan, meets the presidents of both countries May 6-7.

The talks illustrate U.S. anxiety that Afghanistan could again become a haven for al Qaeda militants to launch foreign attacks more than seven years after U.S.-led forces toppled the Afghan Taliban regime that sheltered the September 11 attackers.

Speaking to U.S. lawmakers, Clinton said the Pakistani government had to provide basic services to its people or risk seeing the Taliban, and other extremists, fill the vacuum.

Under pressure from conservatives, Zardari earlier this month signed a regulation imposing Islamic law in Swat, a northwestern valley once one of Pakistan's most popular tourist destinations.

Asked about the matter, Clinton bluntly replied: I think that the Pakistani government is basically abdicating to the Taliban and to the extremists.

Speaking before the House Foreign Affairs Committee, Clinton said, ominously, that the situation in Pakistan poses a mortal threat to the security and safety of our country and the world.

Swat was a major tourist spot until 2007, when militants infiltrated the valley from strongholds on the Afghan border to the west in support of a radical cleric.

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After inconclusive military offensives and a failed peace agreement, Pakistani authorities accepted an Islamist demand for sharia, or Islamic law, in February.

Teresita Schaffer, a former U.S. diplomat who served in Pakistan and now heads the South Asia program at the Center for Strategic and International Studies think tank in Washington, said many analysts share Clinton's assessment.

There is deep concern in the U.S. government, and elsewhere in this country, about the implications of the deal in Swat, Schaffer said. It represents a cession of state authority to people who have been slitting the throats of policemen in the public square.

Schaffer said she did not believe Clinton viewed the Pakistani state itself as a mortal threat.

Rather, she said Clinton may have been suggesting that events in the country, where militants are believed to have plotted foreign attacks and set off a series of domestic suicide bombings in the last month, threaten other nations.

The White House says the May 6-7 talks between Obama, Karzai and Zardari will include a three-way meeting. The talks represent the U.S. president's effort to ease tensions and forge more cooperation between the two countries.

Kabul has accused Islamabad of not doing enough to stop militants crossing the border to launch attacks in Afghanistan. However, ties have improved under Zardari, whose country is facing its own Islamist insurgency.

Obama has authorized the deployment of 21,000 additional U.S. troops and hundreds of new diplomatic and other civilian officials to Afghanistan to try to quell the Taliban insurgency in the south and the east of that country.

A senior U.S. commander said U.S. and NATO forces were close to achieving irreversible momentum in their battle with insurgents in eastern Afghanistan, saying this was partly due to an influx of some 4,000 U.S. troops to the area this year.