Prime Minister David Cameron has said Britain plans to withdraw about 3,800 of its soldiers from Afghanistan by the end of 2013.
About 5,200 British troops are expected to remain into 2014, compared to the 9,000 troops currently.
After 2014, Cameron told parliament that Britain will keep a small number of soldiers in Afghanistan to help train Afghan forces, without saying how many.
Britain has the second-biggest foreign contingent in Afghanistan after the United States.
The unpopular war has cost the lives of more than 430 British troops since the U.S.-led invasion in 2001.
On December 15, France withdrew the last of its combat troops from the country.
Based on reporting by Reuters, AP, and the BBC