The ISI official said his agency knows and works with "the bona fide CIA people in Pakistan" but is upset that the CIA would send others over behind its back. For now, he said, his agency is not talking with the CIA at any level, including the most senior.

To regain support and assistance, he said, "they have to start showing respect, not belittling us, not being belligerent to us, not treating us like we are their lackeys."

NATO and US operations in Afghanistan could be adversely effected by a split between the ISI and the CIA. Washington complains bitterly about Pakistan's refusal to go after the Pakistani-headquartered Haqqani network, which is believed to be the strongest fighting force in Afghanistan and closely allied with al-Qaida.

The ISI official said Pakistan is fed up with Washington's complaints, and he accused the CIA of planting stories about ISI assistance to the Haqqani network.

Relations between the CIA and ISI have been on a downward slide since the name of the US agency's station chief in Pakistan was leaked in a lawsuit accusing him of killing civilians in a drone strike.

Fearing for his safety, the CIA eventually pulled the station chief out of the country. ISI leaders balked at allegations that they outed the CIA top spy in their country. Former and current U..S. officials believe the station chief fell out of favor, but the Pakistanis say this is not the case

Those accusations and the naming of ISI chief Shujah Pasha in a civil lawsuit in the United States _ filed by family members of victims of a November 2008 attack in Mumbai, India, by insurgents _ started the downslide in relations, the ISI official said.

To help repair the crucial relationship, the CIA earlier this year dispatched a very senior officer to be the new station chief who was previously the head of the European Division, one of the most important jobs in the National Clandestine Service, the agency's spy arm.

The spy agencies have overcome lows before. During President George W. Bush's first term, the ISI became enraged after it shared intelligence with the United States, only to learn that the then-CIA station chief passed that information to the British. The incident caused a serious row, one that threatened the CIA's relationship with the ISI and deepened the levels of distrust between the two sides. At the time Pakistan almost threw the CIA station chief out of the country.

CIA spokesman George Little said "issues" between the two agencies will be sorted out.

"The CIA works closely with our Pakistani counterparts on a wide range of security challenges, including our common fight against al-Qaida and its terrorist allies," he said. "The agency's ties to ISI have been strong over the years, and when there are issues to sort out, we work through them. That's the sign of a healthy partnership," he said.