Britons die as US launches offensive.

TWO British soldiers have been killed in southern Afghanistan.

Another six members of Nato forces were wounded in the attack in Helmand Province on Wednesday involving an improvised explosive device. Next of kin have been informed.

The deaths came ahead of a massive US military operation aimed at driving the Taliban from south Afghanistan.

Thousands of Marines poured from helicopters and armoured vehicles into villages in Helmand province in the first major operation under President Barack Obama's stabilisation strategy.

Helmand is a Taliban stronghold and the world's largest opium poppy-producing area. The goal is to clear insurgents from the hotly contested region before Afghanistan's presidential election on August 20.

The Marines did not suffer any serious casualties initially and saw only sporadic resistance, a spokesman said. "The enemy has chosen to withdraw rather than engage for the most part," he said.

The operation came as the US announced that one of its soldiers was missing and believed captured by insurgents in eastern Afghanistan. He was not involved in the Helmand operation.

Officials described the offensive dubbed Khanjar or "Strike of the Sword" as the largest and fastest-moving of the war's new phase and the biggest Marine offensive since that in Iraq in 2004.

It involves nearly 4,000 newly-arrived Marines plus 650 Afghan forces. British forces last week led similar, but smaller, missions to clear out insurgents in Helmand and neighbouring Kandahar.

"Where we go we will stay, and where we stay, we will hold, build and work toward transition of all security responsibilities to Afghan forces," Marine Corps General Larry Nicholson said.