The United States military says US and Afghan forces have exchanged gunfire with Pakistani troops across the border with Afghanistan.
A senior US military official says a five-minute skirmish broke out after Pakistani soldiers fired warning shots near two US helicopters.
No one was hurt in the incidents and the US maintains its troops did not cross the border from Afghanistan.
Cross-border action by US-led forces has angered Pakistan in recent weeks.
The latest incident took place along the Pakistani border with the eastern Afghan region of Khost, an area which is a hotbed of militant groups.
Forces from the US-led coalition and the Nato-led International Security Assistance Force (Isaf) patrol the frontier, but Pakistan has been angered by reported US operations across the border in pursuit of insurgents.
A BBC correspondent says the border between the two countries is very unclear and in effect is marked by a 3km-4km (2-2.5 mile) stretch of no-man's land.
http://news.bbc.co.uk/2/hi/south_asia/7636845.stm
