MARDAN, Pakistan - Helicopters dropped Pakistani commandos into a Taliban stronghold in the Swat Valley on Tuesday, pressing ahead with an offensive the army said had killed more than 750 militants and driven about 800,000 people from their homes.

Despite claims of success in an operation that began after heavy U.S. pressure, the army said it had yet to start operations in the region's main town of Swat, where witnesses say Taliban insurgents are in control and preparing for what could be bloody door-to-door fighting.

Farther south, a suspected U.S. missile attack flattened a house and killed at least eight people in another militant bastion near the Afghan border, officials said, in the latest in a series of attacks that have strained U.S. and Pakistani ties.

Choppers placed troops on "search and destroy" missions in the remote Piochar area in the upper reaches of the Swat Valley, army spokesman Maj.-Gen. Athar Abbas said. Officials have identified Piochar as the rear-base of an estimated 4,000 Taliban militants. It is seen as a possible hiding place of Swat Taliban chief Maulana Fazlullah.

Abbas said the army had yet to begin the "hardcore urban fight", but Interior Minister Rehman Malik expressed optimism the battle might prove short.

"The way they (militants) are being beaten, the way their recruits are fleeing, and the way the Pakistan army is using its strategy, God willing the operation will be completed very soon," he said.

Pakistani authorities launched a full-scale assault on Swat and surrounding districts last week after the Taliban pushed out from the valley on the back of a now-defunct peace deal and extended their control to areas just 100 kilometres from the capital, Islamabad.

It has been praised by American officials, who had been insisting Islamabad must eliminate safe havens used by militants to undermine the pro-western governments in both Afghanistan and Pakistan.

The Pakistani army said Tuesday that troops backed by artillery and air strikes had killed 751 militants in Swat and neighbouring districts so far. It was unclear how it calculated that figure, which couldn't be independently verified. Abbas said the army lost 29 soldiers and had no reports of civilian casualties. Accounts from refugees fleeing the fighting suggest there has been significant loss of innocent life.

The offensive has also unleashed a tide of refugees, whose plight could sap public support for the kind of sustained action against an increasingly interlinked array of Islamist extremists that the cash-strapped country's western backers want to see.

An army officer said Tuesday that the total number displaced in the northwest - including some half-million who fled a separate offensive in the Bajur border region last year - had risen to 1.3 million.

The UN has registered 501,000 refugees from the latest fighting. About 73,000 are living in hot, tented camps established just south of the war zone. Officials acknowledge that many more have taken refuge with relatives without registering with the authorities.

An Associated Press reporter who visited three camps over the last two days found them hot and dusty, but provided with food, shelter and basic medical facilities available.

Officials acknowledge that many more have taken refuge with relatives without registering with the authorities.

The missile strike destroyed a house in Sara Khora, a village in the South Waziristan tribal region, Pakistani security officials said. The identities of those killed were not immediately known.

Two security officials, citing initial intelligence reports, said eight people died. They said agents on the ground were still trying to discover the identities of the victims. The officials asked for anonymity because they are not authorized to speak openly to the media.

Yar Mohammad, a resident of the area, told The Associated Press by telephone that he had seen Taliban militants removing bodies from the building and taking them away in vehicles.

Over the past year, the U.S. has carried out dozens of missile strikes on al-Qaida and Taliban targets in the border area, where American officials say al-Qaida chief Osama bin Laden is likely hiding.

Pakistani leaders publicly oppose the tactic, saying it fuels anti-American sentiment and makes it easier for extremists to recruit. U.S. officials say the strikes, apparently carried out by CIA drones, have killed a string of al-Qaida operatives and minimized civilian casualties.


Associated Press writers Ishtiaq Mahsud in Dera Ismail Khan and Munir Ahmad in Islamabad contributed to this report.