WASHINGTON (REUTERS) - President Barack Obama will announce in his State of the Union address on Tuesday that 34,000 troops will return from Afghanistan by early next year, a source familiar with the speech told Reuters.

"The President will announce that 34,000 troops will be back from Afghanistan a year from tonight," the source said, on condition of anonymity.

Mr Obama and Afghan President Hamid Karzai last month agreed to speed the handover of combat operations in Afghanistan to Afghan forces.

There are about 66,000 US troops in Afghanistan.

Washington's NATO allies have been steadily reducing their troop numbers despite doubts about the ability of Afghan forces to shoulder full responsibility for security.