ISLAMABAD - Pakistani security officials say fighting in the volatile northwest Tuesday morning has killed at least two soldiers and 15 Islamist militants.

They say suspected Islamist militants launched a surprise attack against a security outpost in the Orakzai tribal agency but the raid was beaten back. The fighting seriously wounded several soldiers.

Orakzai is one of Pakistan's seven semi-autonomous tribal regions near the Afghan border. The Pakistani Taliban and foreign militants linked to al-Qaida are active in the area.

Tuesday's attack came as Pakistani troops have been engaged in a counter-militancy offensive in nearby North Waziristan tribal agency since June. The recent spike in militant attacks against security forces is being attributed to the army operations.

Meanwhile, a bomb blast in the southwestern city of Quetta on Tuesday killed at least one person and wounded 20 others, including some policemen.

Provincial authorities say that a judge of an anti-terrorism court appeared to be the target of the bombing. The judge escaped unhurt but his two guards have been wounded. Police say that a car filed with up to 40 kilograms of explosives was parked on the roadside and a remote-controlled device was used to detonate the bomb. Several vehicles were also badly damaged.