He said Pakistani soldiers sounded a bugle call and fired in the air, forcing the helicopters to return to Afghan territory.

Military spokesman Major Murad Khan confirmed that there had been shooting. But he said the American helicopters had not crossed into Pakistani airspace and Pakistani troops were not responsible for the firing.

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.

A spokesman for the US military at Bagram Airbase, north of Kabul, said its forces had not reported any such incident.

The unit in the area belongs to the (US-led) coalition. They are not reporting any such incident, the US military spokesman said.

But the official denials were contradicted by Pakistani civilian officials and villagers in Angor Adda.

One official told Reuters by telephone that the troops stationed at BP-27 post fired at the choppers and they turned away.

Two Chinook helicopters appeared set to land when troops began shooting, alerting tribesmen who also opened fire on the intruders, said a senior government official in Peshawar, the capital of North West Frontier Province.

A resident described the tension in the village through the night. We saw helicopters flying all over the area. We stayed awake the whole night after the incident, he said.

The fiercely independent tribesmen of the region carry weapons regardless of whether they are militants.

... contd.