Washington, Dec 17 - The first of an additional 30,000 troops ordered into Afghanistan by US President Barack Obama have arrived, the Pentagon said Wednesday.

The troops are part of the 1,500 Marines expected to be in place by Christmas, spokesman Geoff Morrell said.

Obama announced December 1 that he was expanding the US presence in Afghanistan to reverse gains made by the Taliban in recent years and stabilize the war-ravaged country.

"The surge has begun in earnest," Morrell said.

Up to 16,000 soldiers received deployment orders days after Obama's announcement. The full force of 30,000 is scheduled to be deployed by the end of summer. The buildup will bring the total US contingency to 98,000. (dpa)