US President Barack Obama will announce a modest increase of 4,000 more troops to Afghanistan as he unveils a new Afghan strategy Friday, US officials said Thursday.

The new troops will be deployed to that country later 2009 and will be assigned to train local police and security forces, the officials were quoted by the web site of the Washington Post as saying.

That increase will raise US troop levels there to 61,000-65,000 troops, doubling America's military presence from last December.

The White House announced earlier in the day that the president will announce the strategy on Friday after two-month internal consultations.

The strategy for Afghanistan is expected to include the contents of increasing US troops, expanding Afghan security forces, and appealing for cooperation from "moderate" insurgents, sources closed to the consultations said.

The move to deploy an extra brigade follows Obama's decision last month to send in 17,000 reinforcements to take on insurgents challenging the Kabul government.

On last Sunday, Obama also said it was crucial to set out "an exit strategy" which will allow the United States to eventually leave the country, after more than seven years of war.

(Xinhua News Agency March 27, 2009)