ISLAMABAD, Pakistan – Pakistan's ISI spy agency is ready to split with the CIA because of frustration over what it calls heavy-handed pressure and its anger over what it believes is a covert U.S. operation involving hundreds of contract spies, according to an internal document obtained by The Associated Press and interviews with U.S. and Pakistani officials.

Such a move could seriously damage the U.S war effort in Afghanistan, limit a program targeting al-Qaida insurgents along the Pakistan frontier, and restrict Washington's access to information in the nuclear-armed country.