Britain will withdraw a further 500 troops from Afghanistan by the end of 2012, bringing its contingent there to 9,000, Prime Minister David Cameron said on Wednesday.

Cameron said he had taken the decision because Afghanistan's fledgling army and police had showed significant progress ahead of the deadline for the handover of security by international forces at the end of 2014.

"Last month, President Obama announced that the US would withdraw 10,000 of its forces by the end of this year and would complete the removal of the US surge -- some 33,000 -- by the end of the summer next year," Cameron said in a statement to parliament.

"At the time of the US surge, the UK increased its core force levels by an extra 500.

"For our part, I have already said we'll withdraw 426 UK military personnel by February 2012 and today I can announce that the UK will be able to reduce its force levels by a further 500 from 9,500 to 9,000 by the end of 2012."

Cameron added: "This decision is not only right for Britain, but it is right for the Afghans too."

His announcement came a day after he returned from a two-day trip to Afghanistan to meet British soldiers and hold talks with Afghan President Hamid Karzai.

Most of Britain's troops are based in the restive southern province of Helmand where they are fighting Taliban militants.