At least 15 militants and four soldiers were killed during clashes in a tribal district in northwest Pakistan, security officials said Saturday.

At least 15 militants and four soldiers were killed during clashes in a tribal district in northwest Pakistan, security officials said Saturday.

The confrontation started on Friday and continued until Saturday morning in Khyber, one of the seven tribal districts along the Afghan border, officials said.

"During exchange of fire, troops killed at least 15 militants and destroyed their two hideouts," a senior security official said.

"Four soldiers were also killed in the operation," the official added.

It was not clear how the clashes began, but Pakistan troops have been targeting Taliban militia in a recent military push in the important Khyber tribal district.

Pakistani troops have been fighting for years against homegrown insurgents in the tribal belt.