Pakistani troops killed nearly 40 suspected militants Sunday in a series of operations in northwestern tribal areas near the Afghan border, officials said.

The army launched an offensive against the Taliban in South Waziristan in mid-October, but many militants fled north to escape the fighting. Sunday's attacks, which could not immediately be confirmed, appeared to be targeting areas to which they escaped.

The deadliest strike was in Shahukhel, a town in the tribal area of Orakzai, in which at least 12 militants were reported killed and 14 detained in search operations by border forces, according to officials with the Frontier Corps.

An attack helicopter also pounded several areas elsewhere in the region, killing at least four militants, intelligence officials said.

At least 11 other suspects, including an insurgent commander, were killed in fighting when the army repulsed an attack in the Bajur region, which was the site of a major operation earlier this year, officials said.

The battle broke out after an army base came under rocket fire. The military had been tipped off to the attack and opened fire on the militant positions, they said.

Officials said 10 other militants were killed in military action elsewhere in Bajur. The military campaign against the Taliban there ended with a declaration of victory in March and continued activity underscores the resilience of the militants who are routed only to return to affected areas.

The officials all spoke on condition of anonymity because they weren't authorized to release the information. Journalists have little access to Pakistan's volatile tribal regions, which makes it virtually impossible to verify the casualty figures.

Army spokesman Maj. Gen. Azhar Abbas said there were air strikes in tribal areas but he provided no details.

The Pakistani military said in a statement Sunday that five insurgents were killed and one soldier wounded in operations in South Waziristan.

The United States has welcomed the Pakistani offensive, but wants the army to do more against the insurgents blamed for violence across the border in Afghanistan.

Pakistan's army has retaken many towns in South Waziristan but many militants fled and have retaliated with a series of clashes and bombings.