Pak-Afghan Border: NATO helicopter incursion into Pakistan's North Waziristan has wounded two security personnel, the incident in the Datta Khel district comes amid tensions between Islamabad and the West following the US raid in Abbottabad in which Osama bin Laden was killed and protests in Pakistan over US drone strikes on its territory.
"It happened early morning," a Pakistani intelligence official in the region, who declined to be identified because he was not authorised to speak to the media, told the Reuters news agency.
"The helicopter hit a Pakistani checkpoint on the border in the Datta Khel area."
The incursion came a day after a drone attack in the same place left seven fighters dead, Pakistani officials said.
Another intelligence official said several Pakistani helicopters took off from Miranshah, the main town in North Waziristan, towards the site of the attack, but the purpose of the Pakistani mobilisation was unclear.
There was no immediate comment from the Pakistani military.
Lieutenant-Commander Colette Murphy, a spokeswoman for the NATO-led International Security Assistance Force (ISAF), said in the Afghan capital, Kabul, that the coalition was looking into the incident. She made no further comment.