Pakistan's army on Wednesday said it scrapped talks with US military officials after a military delegation sent to Washington had to go through "unwarranted" airport security checks.
Mistrust exists between Pakistan and the United States even though they have been allies for decades.
Security at US airports has been especially stringent since the 2001 al-Qaeda attacks on New York and Washington, with scores of passengers complaining they had been singled out for checks due to their "Middle Eastern" or "Muslim" appearance.
The Pakistan delegation was visiting the United States at the invitation of the US military's Central Command (CENTCOM), which oversees the wars in Iraq and Afghanistan.
"The delegation was subjected to unwarranted security checks at Washington airport by the US Transport Security Agency," the army said in a statement.
The delegation was later cleared and US defence officials expressed regret over the incident. The statement did not give the date of the visit.
"However, as a result of these checks, military authorities in Pakistan decided to cancel the visit and called the delegation back," the army said.
In March, a Pakistani parliamentary delegation called off a two-week US trip, sponsored by the state department, after law-makers were tagged for further screening at Washington's airport as they were en route to New Orleans.
Washington sees Pakistan as a vital ally in the fight against militancy and wants it to crack down on Afghan Taliban militants who cross the border to attack US-led NATO troops in Afghanistan.
Mistrust between the two countries involves a range of issues, from security cooperation to how aid is delivered. Anti-American sentiment runs high in Pakistan.
The US has given billions of dollars in aid to Pakistan since it joined its war against al-Qaeda and the Taliban in 2001.
