The district was described as a hub of al-Qaeda and Taliban fighters, who plotted and launched deadly attacks on US and NATO troops in Afghanistan.

The United States has welcomed Pakistan's ongoing operations against the militants across the north-west, as it places the country at the centre of its strategy to turn the tide against the Afghan Taliban.

Pakistani forces have nearly concluded their two-month operation in the Swat valley and its neighbouring areas, and are now gearing up for an offensive against top Taliban commander Baitullah Mehsud and his network in South Waziristan district.

Mehsud, who carries a 5-million-US-dollar bounty on his head for being a key al-Qaeda facilitator, is blamed for a spate of terrorist attacks since 2007 which have killed more than 2,000 people, mostly civilians.