Pakistani forces have cleared militant strongholds from three areas in the South Waziristan region on the Afghan border and 40 militants and eight soldiers have been killed in the fighting, the military said on Thursday.

The army is sending reinforcements and using tanks in the area after a week of fighting with militants loyal to a Taliban commander the government said was behind the assassination of opposition leader Benazir Bhutto last month.

Security forces had carried out operations in three parts of South Waziristan, the military said on Thursday.

"These areas have been cleared of militant strongholds and hideouts," the military said in a statement.

"Forty miscreants have been killed in the last 24 hours and 30 miscreants have been apprehended while many injured," the military said.

Eight soldiers had been killed and 32 wounded, it said.

The fighting is in strongholds of militant commander Baitullah Mehsud, who the United States has also said was behind Bhutto's assassination in a gun and bomb attack in Rawalpindi on December 27.

Mehsud has been blamed for a string of attacks in a suicide bomb campaign that intensified after commandos stormed a radical mosque complex in Islamabad last July.

On Wednesday last week, his men attacked and captured another fort in Waziristan.

Security forces have been battling al Qaeda-linked militants in South Waziristan for several years. The mountainous region, occupied by conservative, independent-minded Pashtun tribesmen, has never come under the full authority of any government.

"APPEASING U.S., BRITAIN"

Militants in South and North Waziristan also attack U.S.- and NATO-led foreign forces and Afghan government troops across the border in Afghanistan.

As the fighting intensified in South Waziristan this week, a top U.S. military commander visited Pakistan for talks with its army chief, General Ashfaq Kayani.

Admiral William Fallon, the head of the U.S. military's Central Command, discussed the security situation with Kayani at his headquarters in Rawalpindi on Tuesday. Officials declined to elaborate.

Fallon told reporters in Florida last week that Pakistan was increasingly willing to fight Islamist militants and accept U.S. help, without saying what kind of support.

But he added that he believed Pakistani leaders wanted a "more robust" effort by U.S. forces to train and advise their forces in counter-insurgency efforts.

The United States has already announced plans to step up training of Pakistan's Frontier Corps, a paramilitary force recruited from tribal lands.

Residents of South Waziristan said they heard heavy fighting through the night in the vicinity of three villages, Spinkai Raghazai, Tanga and Khaisoor, in a Mehsud area.

The fighting subsided just before dawn, a resident said.

In neighbouring North Waziristan, where militants are also active, about 2,500 tribesmen in the town of Mir Ali protested against the military's attacks in South Waziristan.

"These operations are unjustified and are only meant to appease America and Britain," a Muslim cleric, Mehmood-ul-Hassan, told the protesters.

"The government should declare a ceasefire immediately. This can't be resolved through force but only through talks," he said.