More than 2,000 marines were brought to Afghanistan in late April to hunt leaders of the Taliban and Al-Qaeda and destroy their networks.

"As of now I would characterise that we have inflicted in excess of 80 casualties on the anti-coalition militias since we've begun talking about this operation," US-led coalition spokesman Lieutenant Colonel Tucker Mansager said.

The militants have been killed in fighting over the past three weeks in offensives focussing particularly on Zabul province's Deh Chopan district, some 300 kilometres (185 miles) southwest of the capital Kabul.

Previously the coalition has said only that "in excess of 20" insurgents had died in the ongoing offensive, which has involved US warplanes.

Mansager said there had been no significant fighting since Wednesday when the marines fought militants in the mountainous valleys of the Taliban heartland.

"Nothing specific... there have been several attempts to fire either rockets or mortars at our forces with no effect at all," he told a press conference in Kabul.

Kandahar's military commander Khan Mohammed said most of the dead had been killed by bombings in mountains.

"As we go into areas and secure them we find bodies lying here and there," Mohammad told AFP last week.

The marines are based in southcentral Uruzgan but operate frequently in neighbouring Zabul to the east and southern Kandahar province.

Last week US-led coalition troops carried out sweeps of the former Taliban strongholds as part of an offensive aimed at stemming a spiral of violence in the lead-up to elections slated for September.

On Thursday 11 Chinese road construction workers were killed by gunmen in an overnight attack on their camp in northeastern Kunduz province. On June 2 three Europeans and two Afghans working for the Medecins Sans Frontieres aid group were shot dead in northwestern Badghis province.

The marine's operations have also come against a background of renewed activity by the Pakistani army in the tribal regions along the countries' common border.

Mansager said there had been "no particular increase" in cross border activity in the southeast of Afghanistan since the latest Pakistani operation began.

Meanwhile, US marines also captured a bombmaker believed to be a "medium value target" on Friday in an area some 70 kilometres south of Kabul, Mansager said, without giving any further clarification of the location.

"Because he is now a detainee we won't release his name," he said. "However, we can confirm he was a known maker of improvised explosive devices and he was detained during that operation in which no shots were fired nor was there any damage to personel or equipment."

Mansager said a medium-value target was "not merely a foot soldier as in a terrorist who merely totes a weapon" but a person who has a particular expertise such as bomb making.

"But is not a key leader or a controller of subordinate units," he added.

WAR.WIRE