Defense Secretary Philip Hammond added, however, that "I would not expect it to be the majority," reported The Associated Press.
The secretary's remarks suggest that the UK could pull as many as 4,500 personnel from the country next year, said Reuters.
Britain is set to pull 500 troops from the country within the year, according to Reuters, reducing its contingent there to some 9,000.
The UK, along with the entire international coalition in Afghanistan, is set to withdraw all troops by 2014.
AP said 433 British soldiers have been killed in Afghanistan since 2001.