British troops will hand over control of the violence-wracked Sangin area of southern Afghanistan to US forces by the end of the year, Defence Secretary Liam Fox announced yesterday.

British forces have suffered their heaviest losses in Sangin with almost 100 deaths in the market town and surrounding areas - nearly a third of their total casualties since military involvement in Afghanistan began in 2001.

Britain was keen to portray the move as a logical redeployment, but the Taliban insurgency claimed credit for the move and warned that the US troops set to take over in Sangin would face "the same fate."

Mr Fox said the Nato-led International Security Assistance Force (ISAF) would restructure its operations in southern Afghanistan "so that it can consolidate a US Marine brigade in northern Helmand which will assume responsibility for security in Sangin later this year.

"This will simplify current command arrangements and enable UK troops to be redeployed to reinforce progress in the key districts of central Helmand," he told the House of Commons.

About 1,000 Royal Marines are expected to leave Sangin and be redeployed to central Helmand by the end of the year.