(New story, with militant attack in South Waziristan)

JAMRUD, Pakistan, Sept 7 (Reuters) - Five Pakistani soldiers were killed in a landmine blast in the Taliban bastion of South Waziristan on Monday a day after forces killed 33 militants as part of a week-old campaign in the Khyber Pass, officials said.

Militant violence has increased in the northwest since commander Hakimullah Mehsud was appointed Taliban chief after the murder of al Qaeda ally Baitullah Mehsud in a U.S. drone strike in South Waziristan on Aug. 5.

The landmine blast struck a routine military patrol on a road leading to Wana, South Waziristan's main town.

"The patrol was sent ahead of a military convey to check the security on the road and a landmine laid by militants went off and killed five soldiers," an intelligence official in Wana, who declined to be identified, told Reuters.

Residents said an exchange of fire also took place between security forces and militants. There was no word on casualties.

There are strong links between Taliban movements in Pakistan and Afghanistan, where violence is also increasing as militants battle the authorities and foreign troops supporting them.

On Sunday, troops killed 33 militants during the latest action to pacify the Khyber Pass, the main land route used to supply Western and Afghan forces in Afghanistan.

Based on official statements, nearly 120 insurgents have been killed in the past week, but independent casualty estimates are unavailable.

The military swung into action in Khyber, one of Pakistan's seven semi-autonomous tribal regions, days after a suicide bomber killed 22 border guards.

Aside from militant factions based in Khyber, other fighters fled there to escape an assault further east on the Taliban stronghold in the Swat valley, where the army went on the offensive in late April.

Truck convoys carrying supplies to U.S., NATO and Afghan forces regularly come under attack as they trundle through the pass that links Pakistan and Afghanistan.

During Sunday's fighting, troops cleared two militant compounds and demolished 17 houses said to belong to insurgents.

"Security forces targeted two militant centres. They destroyed them and killed 33 militants in the operation," a Frontier Corps spokesman said in a statement.

The show of force in Swat and elsewhere has helped allay fears among Western allies that the nuclear-armed Muslim nation was failing to confront spreading Islamist militancy. (For more Reuters coverage of Afghanistan and Pakistan, see:http://www.reuters.com/news/globalcoverage/afghanistanpakist an) (Reporting by Ibrahim Shinwari and Hafiz Wazir; Writing by Kamran Haider; Editing by Simon Cameron-Moore and Ron Popeski)

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