The CIA's Islamabad station chief, who oversaw the intelligence team that uncovered Osama bin Laden's hideout, has left Pakistan for medical reasons, a US official said.

The CIA declined to comment on the matter.

"The chief of station is a respected, senior officer who had the full faith and confidence of folks back in Washington," the US official told AFP on condition of anonymity.

"Most people will agree the officer's role in one of the greatest intelligence victories of all time means this person was pretty darn effective, no matter what the Pakistanis may think."

ABC News, citing US and Pakistani officials, said the officer who headed one of the Central Intelligence Agency's most sensitive positions worldwide was not expected to return.

It was the second such departure in seven months from the post, after his predecessor was forced to leave when a Pakistani official admitted his name had been leaked.

Despite the quick turnover at the key office, US officials told ABC that it would not hamper US intelligence efforts in Pakistan.

US and Pakistani officials told ABC they hoped the station chief's departure would pave the way for smoother ties between the CIA and Pakistan's ISI intelligence agency, noting the departing officer had an "extremely tense" relationship with his counterparts in the ISI.

Relations between the two intelligence agencies has been under great strain in the wake of the raid that killed bin Laden near the country's main military academy.

President Barack Obama's administration recently suspended about a third of its $2.7 billion annual defense aid to Pakistan, but assured Islamabad it is committed to a $7.5 billion civilian assistance package approved in 2009.

And Washington has complained of how Pakistan treats its military and intelligence officials in the country.

"Pakistan has been harassing U.S. personnel working in the country for months," a US official told ABC.

A Pakistani intelligence official, meanwhile, said "there is no trust."