Troops retaliated with artillery fire after the rocket attack Saturday night on their base in Dattakhel, a village in North Waziristan tribal region, which borders Afghanistan, the official said on condition of anonymity because of the secretive nature of his job.

It was not known whether there were any casualties among the militants, who have kept up a stream of the assaults against security forces in the region in recent weeks.

Two children a 3-year-old girl and her brother, 6 were injured when a stray artillery shell struck their home in Manzarkhel, a village just over a mile west of the military base, during a brief exchange of fire between security forces and the militants, he said.

Meanwhile, two soldiers and two policemen were killed and 18 injured in separate bomb blasts yesterday in the restive southwestern Pakistani province of Baluchistan, officials said.

Two paramilitary soldiers were killed and ten injured in two back-to-back bomb explosions at a farm in the town of Kohlu, 300km east of Quetta, a security official told AFP.

The farm is owned and run by the paramilitary Frontier Corps.

"Two soldiers were killed, while 10 were injured, two of them critically," the official said, requesting anonymity.