Pakistani officials are warning the United States risks losing an ally if it continues to publicly accuse Islamabad of being involved in attacks on U.S. targets in Afghanistan.

On Thursday, the chairman of the U.S. Joint Chiefs of Staff, Admiral Mike Mullen, told U.S. lawmakers that the al-Qaida-linked Haqqani network, acting with support from Pakistan's military spy agency, planned and conducted the last week's assault on the U.S. Embassy and NATO headquarters in Kabul.

Pakistani Foreign Minister Hina Rabbani Khar hit back at the criticism, telling a private Pakistani news channel late Thursday that the United States cannot afford to alienate the Pakistani government or its people. Khar said that if the United States chooses to push Pakistan away, it will do so at its own cost.

Pakistani Prime Minister Yousuf Raza Gilani told reporters in Karachi Friday that the U.S.-Pakistani relationship is fraught with difficulty, saying “they can't live with us [and] they can't live without us.”

Mullen said that among other attacks, Pakistan's Inter-Services Intelligence also supported the September 10 car bombing of a a NATO base in the central Afghanistan Wardak that wounded 77 U.S. soldiers.

Mullen said the ISI uses the Haqqani network as a “veritable arm” to act in Afghanistan against Afghan and coalition forces and expressed concern about the impunity with which extremist groups are allowed to operate from Pakistan.

Washington maintains that Haqqani militants take shelter in sanctuaries across the border in Pakistan's North Waziristan tribal region in between attacks in Afghanistan.

Pakistan has repeatedly rejected such accusations by the United States.