Afghanistan - U.S.-led NATO troops launched an offensive on Saturday designed to seize control of the Taliban's last big stronghold in Afghanistan's most violent province, a Reuters witness said.

The assault, the first since U.S. President Barack Obama ordered 30,000 extra troops to Afghanistan in December, is the start of a campaign to impose government control on rebel-held areas this year, before U.S. forces start to withdraw in 2011.

The first wave of several helicopters has left, a Reuters reporter with the 1st Battalion, Sixth Marine Regiment said.

A dozen helicopters flew from south of Marjah and were due to land in the town center, the reporter said.

About 4,500 U.S. Marines, 1,500 Afghan troops and 300 U.S. soldiers are taking part in the offensive in Marjah, in Helmand Province.

One local Taliban commander, Qari Fazluddin, told Reuters earlier some 2,000 fighters were ready to fight in Marjah, a densely populated area.

(Writing by Michael Georgy; Editing by Louise Ireland)

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