Troops backed by helicopter gunships and artillery pounded militant positions in northwest Pakistan, killing 60 fighters and wounding many others, the military said Saturday.

The assault happened Friday evening in the Swat valley shortly before a senior U.S. official arrived in Pakistan for talks with leaders of a country vital to Western security concerns.

Assistant U.S. Secretary of State Richard Boucher held talks in Islamabad on Saturday morning with Pakistan's Interior Ministry chief Rehman Malik and was expected to meet other leaders later in the day. He made no public comment.

U.S. officials, concerned about rising militancy in both nuclear-armed Pakistan and neighbouring Afghanistan, have praised Pakistani efforts to clear Taliban and al-Qaida strongholds near its northwestern frontier.

But militants are mounting stiff resistance including a string of suicide attacks that could fan widespread Pakistani concern that it is paying too high a price for its front-line role in the U.S.-led war on terror.

An army statement said Friday's offensive killed at least 60 militants and wounded many more near the town of Matta.

It was not immediately possible to independently confirm the casualties. Reporters cannot visit the area because of poor security and government restrictions. No Taliban spokesman was available for comment.

Strife over efforts to establish Taliban-style rule

The army didn't mention any losses among government forces.

Swat was once a popular tourist destination, but the region has become a battleground since last year when Pakistan sent troops to confront Mullah Fazlullah, a hardline cleric who launched a violent campaign to enforce Taliban-style Islamic law.

The army said Matta was the same area where it recovered alive one of two Chinese telecommunications engineers who had been held hostage by Taliban militants. It said militants still held the second Chinese man but efforts were under way to rescue him.

The pair disappeared in the nearby Dir region on Aug. 29 while servicing equipment.