* U.S. says Pakistan must show commitment to fight Taliban * U.S. congressman says 'Pakistan's pants are on fire' * Karzai says U.S.-Afghan relations good despite strains (Adds State Dept. comment on joint investigation) By Arshad Mohammed and Paul Eckert WASHINGTON, May 5 (Reuters) - The United States on Tuesday pressed Pakistan to confront Taliban militants whose influence is spreading in the nuclear-armed country but said it solidly supports Pakistani President Asif Ali Zardari. "Pakistan must demonstrate its commitment to rooting out al Qaeda and the violent extremists within its borders," Richard Holbrooke, the U.S. special representative for Afghanistan and Pakistan, said in prepared congressional testimony. U.S. President Barack Obama meets the Afghan and Pakistani presidents in Washington on Wednesday for talks expected to focus on fighting the Taliban's insurgency in Afghanistan as well as its growing influence in neighboring Pakistan. [nN04433219] The three-way talks aim to promote cooperation between Afghanistan and Pakistan, which Taliban militants use as a base to attack Afghan targets, but have been overshadowed by U.S. concerns about Pakistan's stability. U.S. officials are worried about the strength of Pakistan's Taliban militants, who have advanced beyond a stronghold in the Swat valley, to Buner valley, 60 miles (97 km) northwest of the capital, Islamabad. Pakistani security forces launched an offensive to expel militants from Buner and another district on April 26. About 180 militants have been killed, according to the military, although there has been no independent confirmation. Hundreds of people fled the Swat valley's main town on Tuesday after a Pakistani official warned of possible fresh fighting between government forces and the militants. [nISL504647] The Pakistani government offensive follows criticism by American officials, lawmakers and analysts who accuse Zardari of having done too little to undercut the Taliban. U.S. Secretary of State Hillary Clinton recently accused Pakistan of abdicating to the Taliban and raised the specter of militants seizing its nuclear arsenal. Obama later played down the latter fear. 'PAKISTAN'S PANTS ARE ON FIRE'? Despite the criticism, Holbrooke sent an unambiguous signal of support for Zardari, widower of former Pakistani Prime Minister Benazir Bhutto, who was assassinated in 2007. "We have the highest strategic interests in supporting this government," Holbrooke said. "Our goal must be unambiguously to support and help stabilize a democratic Pakistan headed by its elected president, Asif Ali Zardari," he said. Holbrooke, who brokered the 1995 peace agreement that ended the Bosnian war, dismissed the idea that Pakistan is disintegrating and said it was not a "failed state." Still, U.S. lawmakers voiced deep concern about Pakistan during the hearing, sometimes in blunt terms. "Pakistan's pants are on fire." said Rep. Gary Ackerman, a Democrat who launched a scathing criticism of Zardari. "Zardari has said the right things ... but in practice his government's response has been slow, weak and ineffective," Ackerman said. "The fire is real and they need to respond." Holbrooke said Pakistan was vitally important to the United States both to help stabilize Afghanistan and to prevent either country from becoming a springboard for attacks on U.S. targets. Al Qaeda leader Osama bin Laden orchestrated the Sept. 11 attacks from Afghanistan, where he was sheltered by a Taliban regime that U.S.-led forces toppled in late 2001. More than eight years later, the United States is grappling with a revived Taliban insurgency and Obama has announced plans to increase the number of U.S. troops in Afghanistan by more than 20,000 this year. After initially voicing frustration with Afghan President Hamid Karzai and his government's perceived ineffectiveness and corruption, Obama aides have since tempered their criticism. Karzai has also muted his criticism of the United States, and said in a speech at a Washington think tank that ties were "very, very solid" despite friction on aid policy, corruption and the deaths of Afghan civilians in U.S. bombing. [nN0531003] State Department spokesman Robert Wood announced a joint investigation into reports that scores of civilians had been killed by U.S. air strikes in a battle with the Taliban in Afghanistan's Farah Province. "The United States deeply regrets any injury or loss of life among innocent Afghans resulting from operations in which its forces are involved," Wood said in a statement. "We take all reports of such incidents seriously and investigate them thoroughly." Karzai said Pakistan -- whose intelligence services have long been accused of maintaining ties to militant groups in Afghanistan -- needed to sever such links. "We must seek from Pakistan a very clear moving away from whatever links that there may be with radical forces or the use of radicalism," Karzai said. (Additional reporting by John Whitesides, Paul Eckert, Sue Pleming; Editing by Alan Elsner and Simon Denyer)
U.S. Special Representative for Afghanistan and Pakistan Richard Holbrooke listens to opening statements as he prepares to testify before a House Foreign Affairs Committee hearing on 'The Future of the US-Pakistan ...
