(CNN) -- Afghan President Hamid Karzai said Thursday he welcomed plans by Britain to withdraw almost 4,000 troops from Afghanistan by the end of next year.
Afghan security forces are ready to ensure security and protect their country, Karzai said, according to a statement from his office.
British Prime Minister David Cameron said Wednesday that UK troop numbers would reduce to about 5,200 by the end of 2013.
UK Defence Secretary Philip Hammond said the accelerated withdrawal was thanks to "real progress" on the ground in the southern province of Helmand.
"This is a direct result of the success of the Afghan National Security Forces in assuming a lead role in delivering security for the Afghan people," he said.
"There remain huge challenges ahead for the Afghan people. Our combat mission is drawing to a close, but our commitment to the Afghan people is long term."
Karzai said the UK announcement was "a timely decision for the security responsibilities to be transferred to Afghan forces."
There will be about 9,000 British military personnel in Afghanistan by the end of this year.
Britain's announcement comes only days after the last French combat units left Afghanistan. About 1,500 French troops will remain in Afghanistan into 2013 to remove equipment and help train Afghan forces.
Britain is the second-largest contributor of troops to the NATO-led International Security Assistance Force, with the majority of its personnel operating in Helmand.
The United States, whose troops make up the bulk of the force, still has some 68,000 personnel in Afghanistan.
Coalition forces are working to get Afghan security forces ready to take charge of security after the NATO mission in Afghanistan concludes at the end of 2014.