KABUL - The US military Thursday began a large-scale offensive against the Taliban in Helmand province in southern Afghanistan as a local militant commander said the Taliban had captured a US soldier.

The US military said the Taliban was believed to have captured the soldier, who has been missing since Tuesday, in the southeastern Afghan province of Paktika.

Mullah Sangon, a local Taliban commander, said that besides the US soldier, the militants had also captured three Afghan soldiers.

Meanwhile, the offensive in Helmand marked the beginning of the implementation of US President Barack Obama’s new strategy in Afghanistan that aims to step up the fight against the militants.

Around 4,000 US marines and 650 Afghan soldiers were taking part in Operation Khanjar, which began early Thursday, a US military spokesman said.

Helmand is a stronghold of the Taliban.

The US and Afghan militaries made no comment about casualties in the offensive, but Taliban spokesman Kari Jussif Ahmadi said the militants killed “more than a dozen” foreign troops and suffered no casualties themselves. The Taliban’s casualty reports, however, are widely considered to be exaggerated.

Ahmadi also claimed that “the foreign troops bombed civilian sites instead of hideouts of the Taliban”. The Islamist fighters had taken cover in secure sites, he said.

Daud Ahmadi, a spokesman for Helmand’s governor, said 1,000 Afghan security personnel were fighting alongside the 4,000 Americans. He added that civilian reconstruction would follow on the heels of the military operations.

The aim of the Helmand offensive is to drive the Taliban out of Helmand, media reports said, citing US military spokesmen.

The soldiers are attempting to set up a series of bases in Helmand. The aim is to improve the security situation in the province, Brigadier General Larry Nicholson said.

The US has reportedly deployed about 8,500 marines in Helmand in the past two months. As part of Obama’s new strategy, the US contingent in Afghanistan would be strengthened by an extra 21,000 soldiers and there would be a new emphasis on civil and economic aid.

Obama is prioritising the war against the Taliban in Afghanistan and in neighbouring Pakistan over the war in Iraq, where US troops withdrew from cities and towns Tuesday.

General Stanley McChrystal, a specialist in covert operations, replaced David McKiernan as the US commander in Afghanistan in mid-June after the security situation there noticeably deteriorated.

Militants carried out more than 400 attacks in the first week of June, according to General David Petraeus, US commander in the Middle East and Central Asia. That was the highest figure since the US-led military toppled the Taliban regime in 2001.

In June last year, there were fewer than 250 Taliban attacks per week, and in January 2004, there were fewer than 50 per week, a spokesman for the four-star general said.