KABUL, Afghanistan - U.S.-led forces rained fire for two days on militants near Afghanistan's border with Pakistan, officials said Monday, killing about 55 insurgents and underscoring how fighting with Taliban insurgents is escalating.

The battle in eastern Paktika province was the second in the past week to reportedly inflict major casualties on militants, whom Afghan officials insist are swarming in from strongholds in Pakistan.

Pakistan's government Monday reiterated an offer to fence the craggy, 2,400-kilometre frontier -- a project begun but abandoned last year amid criticism that it would only enrage the tribes who straddle the frontier and among whom the Taliban find many recruits.

The battle in Paktika began Friday morning, when militants armed with rockets and guns ambushed troops from the U.S.-led coalition patrolling a road in Ziruk district, the coalition said. The troops returned fire and called in air strikes.

Fighting continued until Sunday morning, and the majority of the deaths were from the air strikes, coalition spokesman Capt. Christian Patterson said. About 55 militants died, 25 others were wounded and three were detained, he said.

Patterson said no coalition troops died, but declined to say if any were wounded.

It was not possible to get independent confirmation of the death toll, but Nabi Mullakhail, the provincial police chief, said militants had suffered "huge" casualties in the remote, mountainous district. Afghan forces were not involved, he said.

The clash was the second in a week to inflict heavy casualties on insurgents, who have little answer to western airpower.

The Afghan Defence Ministry said its soldiers counted the bodies of 94 militants after a joint operation with NATO forces last week in Arghandab, a valley just outside the southern city of Kandahar.

The latest deaths means that June is already the bloodiest month this year.

According to an Associated Press tally based on statements from military and government officials, 465 people have died in insurgency-related violence this month, more than the 398 recorded in April.

For the year to date, the tally is nearing 2,000, most of them militants.

Violence was escalating because of stepped-up military operations by the more than 60,000 foreign troops in Afghanistan, said Mustafa Alani, director of security and terrorism studies at the Dubai-based Gulf Research Centre.

Alani said the Taliban were exploiting anger at reports of civilian casualties in military operations and successes such as a mass jailbreak in Kandahar to recruit new fighters.

The insurgents have become more adept at Iraq-style guerrilla tactics, including roadside bombs, he said.

"The number of casualties is not a measure of victory or defeat for them (the Taliban)," Alani said. "Those people are viewed as martyrs."

NATO said its forces prevented four militants from planting a bomb on a road in eastern Nangarhar province Monday, but denied reports that two civilians died.

After a gunbattle, it said the troops called in air support, killing one militant. The others fled.

However, Zalmay Dadak, mayor of Khogyani district, said coalition fire during the overnight operation also hit a house in a village, killing a man and his son. More than 100 villagers blocked the road in protest for several hours Monday.

Video footage obtained by Associated Press Television News showed the corpses of a young man and a boy lying on wooden beds under trees in the village Monday. Residents said a hole in the roof of the family's house was caused by a shell.

The violence highlighted the need for regional and western governments to seek political solutions to a conflict that shows no sign of easing, said Charles Dunbar, professor of international relations at Boston University and former U.S. diplomat.

As part of that, "Pakistan can perhaps do more than it is doing to control the free movement of the Taliban" as well as its current policy of seeking peace deals with militants on its side, he said.

Fencing the border is mainly a political figleaf for the hard-pressed Pakistani government, he suggested. "This is an effort on their part to look busy," he said.