Pakistan has issued a strong protest to NATO after two of its soldiers were wounded by NATO helicopters from Aghanistan.

Pakistan's military says troops fired on the choppers when they violated the country's airspace on Tuesday.

A western military official in Kabul says the helicopters were in Afghanistan and returned fire, but local witnesses say the aircraft fired first.

Pakistan has demanded a meeting with NATO officials.

The incident comes after US Senator John Kerry attempted to soothe tensions between the United States and Pakistan following the killing of Osama bin Laden.

AFP reports that the region is being targeted by a record number of US drone strikes, with more than 100 strikes killing over 670 people in the past year.