Islamabad: Pakistani troops fired shots to stop US military helicopters from crossing into Pakistani territory and forcing them to return to Afghanistan on Monday, Pakistani security officials said.

The incident took place in the village of Angor Adda in the South Waziristan region, the site of a bloody US strike earlier in the month, where at least 20 people were killed.

"The U.S. choppers came into Pakistan by just 100 to 150 metres at Angor Adda. Even then our troops did not spare them, opened fire on them and they turned away," one security official said.

Another security official said US armoured vehicles were seen on the Afghan side of the border, and US warplanes were seen overhead.

Pakistani soldiers sounded a bugle call, before firing in the air, forcing the helicopters to return to Afghan territory.


However, military spokesman Major Murad Khan said American helicopters did not cross into Pakistan airspace, but confirmed that there had been shooting.

"The US choppers were there at the border, but they did not violate our airspace," Khan said.

"We confirm that there was a firing incident at the time when the helicopters were there, but our forces were not involved."

Last week, Pakistani army chief General Ashfaq Kayani issued a stern statement warning that Pakistan would not allow foreign troops onto its soil and Pakistan's sovereignty and territorial integrity would be defended at all cost.