Pakistan's army chief is dismissing U.S. accusations that its military spy agency supports al-Qaida-linked militants who attack American targets in Afghanistan as “not based on facts.”

U.S. officials have long maintained that Haqqani militants attack U.S. targets in Afghanistan and then take shelter in sanctuaries across the border in Pakistan's North Waziristan tribal region. On Thursday, the chairman of the U.S. Joint Chiefs of Staff, Admiral Mike Mullen, took the criticism a step further, saying the Haqqani network is a “veritable arm” of Pakistan's Inter-Services Intelligence.

He said that among other attacks, the ISI supported the Haqqanis' assault last week on the U.S. Embassy and NATO headquarters in Kabul, as well as the September 10 car bombing of a NATO base in central Afghanistan that wounded 77 American soldiers.

In a statement Friday, Pakistan's army chief General Ashfaq Pervez Kayani blasted Mullen's comments as a “blame game” and categorically denied the accusations that Pakistan is conducting a Pakistani proxy war in Afghanistan and that the ISI is supporting the Haqqanis.

He said Mullen's statements were “especially disturbing” considering the two men had what the Pakistani general called a “rather constructive” meeting earlier this month in Spain.

Kayani also said singling Pakistan out is “neither fair nor productive,” implying that Pakistan's contacts with the Haqqanis are part of ongoing reconciliation efforts.

Earlier Friday, White House Press Secretary Jay Carney said it is critical that Pakistan “break any links” it has with the Haqqani network. He also urged Islamabad to take immediate action against the militant group to ensure it is no longer a threat to the American or Pakistani people.

Pakistan has repeatedly rejected any U.S. accusations that it helps militants, including the most recent and pointed allegations. Pakistani Foreign Minister Hina Rabbani Khar hit back at Mullen's remarks late Thursday, warning that the United States risks losing an ally if it continues to make such statements.

Khar told a private Pakistani news channel late Thursday that the United States cannot afford to alienate the Pakistani government or its people. The Pakistani foreign minister said that if the United States chooses to push Pakistan away, it will do so at its own cost.

In Karachi, Pakistani Prime Minister Yousuf Raza Gilani told reporters 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.”