While an expected surge in the number of U.S. troops in Afghanistan next year will be welcomed by NATO forces there, their arrival could herald an increase in violence, says a senior spokesman for those forces.

U.S. president-elect Barack Obama could send up to 12,000 more U.S. troops to Afghanistan in the spring. They would join 50,700 NATO-led International Security Assistance Force soldiers, of which 2,500 are Canadian.

But there will be more confrontations with Taliban forces as additional U.S. forces arrive, said Brig.-Gen. Richard Blanchette, a Canadian who serves as a spokesman for ISAF.

"There is a risk that it gets worse before it gets better - when you have more troops, you have more interface between the insurgents and the forces from ISAF," Blanchette said Wednesday during a visit to Kandahar Airfield.

Blanchette did not say whether he thinks the increased instances of conflict will lead to more casualties.

For the first time ever, the average number of daily insurgent attacks in Afghanistan exceeded those in Iraq from August through October.

Half of those were directed against Canadian and other foreign troops, the rest at Afghan security forces and civilians.

Blanchette stressed that Afghan troops are taking on an increasingly prominent role in combating insurgents.

"It is a reality that the Afghan National Army has taken a lead in a lot of the operations. They are much more involved than before," Blanchette said.