Tribal militants killed seven troopers and lost 23 of their own fighters in an attack on a paramilitary convoy in northwest Pakistan early on Monday morning, said an army officer who requested anonymity.

The attack took place in Mohmand, which adjoins Bajaur, another tribal region on the border with Afghanistan, known to be a hotbed of support for groups allied to al Qaeda.

"The fighting broke out at 7:30 when militants attacked a paramilitary convoy," the officer said.