ISLAMABAD, Jan 10 (Reuters) - Pakistan on Wednesday rejected a U.N. official's accusation that Taliban leaders could be hiding in Pakistan, saying military forces in Afghanistan should do more to curb insurgents. Chris Alexander, a deputy U.N. representative in Afghanistan, said on Monday the rebels were operating networks in Afghanistan and Pakistan and urged Islamabad to do more to curb militant activities on its side of the border. Pakistan's foreign ministry rejected Alexander's remarks. "Pakistan is not solely responsible for taking action against militants and terrorists," the ministry's spokeswoman said. "To capture undesirable elements and prevent them from entering into Pakistan is the responsibility of the forces operating on the Afghan side," she said in a statement. While Alexander called on both neighbours to end a war of words over Taliban activities, he urged Pakistan to take action against militants, particularly in Quetta. Taliban leaders run their insurgency from the southwestern Pakistani city, according to Afghanistan and its allies. Alexander said only a handful of Taliban leaders on a U.N. terrorist list had been captured, reconciled with the Afghan government or otherwise accounted for. The Pakistani spokeswoman rejected suggestions about the presence of Taliban leaders on Pakistani soil as "unsubstantiated". She said Pakistan had arrested several Taliban figures, and asked how many rebel leaders on the list had been arrested by Afghan and foreign forces operating in Afghanistan. Ties between Pakistan and Afghanistan, two major U.S. allies in the war on terrorism, have deteriorated sharply over the past year, because of Afghan accusations that the Taliban has sanctuaries in Pakistan. Pakistan, the main backer of the Taliban before the Sept. 11, 2001 attacks in the United States, denies helping the Taliban but says some militants do cross the porous border into Afghanistan. To stem the criticism, Pakistan last month announced plans to fence and mine parts of the 2,500-km (1,553 miles) long border to stem militant activities. Afghanistan is against the proposal, saying it would unfairly split ancient clan ties. The Afghan government on Wednesday said it has sent a letter to U.N. Secretary General Ban Ki-moon to put pressure on Pakistan to abandon the plans. "Afghanistan's government has expressed its deep concern about the fencing and mining," foreign ministry spokesman Sultan Ahmad Bahin told reporters in Kabul, referring to the letter to the U.N. chief.
