The US military on Friday canceled plans to send a 3,500-strong Army brigade to Iraq because of improving security conditions there, possibly freeing up troops for the war in Afghanistan.

The 1st Infantry Brigade Combat Team from the 10th Mountain Division based in Fort Drum, New York, had been scheduled to relieve another combat brigade in Iraq in January but will not deploy, the Defense Department said in a statement.

With the US commander in Afghanistan asking for major reinforcements, the move could provide another brigade for the troubled mission if President Barack Obama decides to approve the troop request.

"The decision was based on a thorough assessment of the security environment in Iraq and reflects the continued improvement in the ability of the Iraqi Security Forces to safeguard Iraqi citizens and institutions," the statement said.

The brigade "will return to the Army's pool of available combat forces," it said.

The US commander in Iraq, General Ray Odierno, has said he wants to retain a larger force in the country to maintain security for elections due in January before a planned drawdown of forces down to 50,000 by the end of August 2010.

About 119,000 US troops are currently stationed in Iraq, down from about 140,000 at the beginning of the year.

Defense Secretary Robert Gates said last month that if Obama approves a troop buildup in Afghanistan, the first reinforcements would not arrive on the ground until January.

US troop levels are to reach 68,000 in Afghanistan by the end of the year.