Chairman of the U.S. Joint Chiefs of Staff Admiral Mike Mullen on Thursday accused the Pakistani government of supporting the al-Qaeda-linked Haqqani network.

Mullen called the Haqqani network a "veritable arm" of Pakistan's Inter-Services Intelligence (ISI), the country's spy agency, as he testified before the Senate Armed Services Committee on the U.S. strategy in Afghanistan and Iraq.

He said the ISI-supported Haqqani network was behind recent attacks in Afghanistan including the Sept. 11 truck bomb attack and the Sept. 13 assault on the U.S. embassy in Kabul.

Mullen, who steps down next week, said the Pakistani government's link to the extremist group would undermine the already troubled U.S.-Pakistani relationship as well as the U.S.-led counterterrorism campaign in Afghanistan.

Pakistan dismissed U.S. accusations that the ISI is using the Haqqani network for a proxy war in neighboring Afghanistan.

Speaking at a regular weekly briefing on Thursday, Pakistan Foreign Office spokesperson Tehmina Janjua said Pakistan has no cooperation with the Haqqani network and was not fighting any war through the Haqqanis in Afghanistan.