Pakistan has stopped all NATO supply trucks from crossing a border checkpoint into Afghanistan, after a NATO helicopter attacked a military checkpoint close to the border.
It says three Pakistani soldiers were killed in the incident on Thursday.
The BBC reports that NATO has confirmed an aircraft crossed the border and opened fire as the crew believed they were being fired on.
NATO says the helicopter was "operating in self-defence".
Pakistan says it "strongly disapproves" of violation of its sovereignty.
Interior Minister Rehman Malik said afterwards that "we will have to see whether we are allies or enemies".
The BBC reports a queue of about 100 NATO vehicles was waiting to cross the border into Afghanistan earlier on Thursday.
