The sources said that a large number of militants entered Meer Kani, Soun, and Dami areas of Chitral from Afghanistan and attacked the check-posts of the paramilitary force, killing 40 and injured several others.
They said that the dead included police officials and Chitral Scouts, adding that some 12 militants have also been killed in retaliatory attack by the forces.
Chitral DCO said that the Scouts have destroyed contact bridges near Afghan border to prevent the militants from escaping.
They said that shootout between the forces and militants were still continued in the areas, adding that the militants were using sophisticated weapons in the battle.
The militant often launched cross border attacks in Pakistani territory, killing hundreds of civilians and security personnel.
The militants are believed to be members of Tehreek Taliban Pakistan (TTP) who had taken shelters in Afghanistan after Pakistan launched military campaign in Swat valley.
Pakistan has long launched protest with the Nato led forces in Afghanistan over the cross border attacks.