Britain is to announce that it will withdraw its 1,000 troops based in the Sangin area of Afghanistan, where the UK has lost about a third of the 311 of its soldiers killed in the war. In a major re-organisation of the Nato deployment in Helmand province, where Sangin lies, Liam Fox, defence secretary, will announce on Wednesday that UK troops are to be replaced by US forces. It is thought likely that the replacement will take place in October, when British troops currently deployed in Sangin will return to the UK. Those that replace them will be posted elsewhere in the country. Natos decision will come as a big relief to British forces in Helmand, where the UK has suffered unusually heavy losses this year. Sangin is particularly dangerous because it contains a patchwork of rival tribes and is a major centre of Afghanistans opium-growing industry. However, Mr Fox and Britains defence chiefs will come under pressure to fend off claims that Britains withdrawal is a retreat from an area where the UK military has been unable to get a grip on the tribal structure and where it has lost 99 troops since 2006. In a bid to pre-empt criticism of the move, the Ministry of Defence on Tuesday night said: UK forces continue to make real progress across Helmand including in Sangin, one of the most contested and challenging areas in southern Afghanistan. Since the start of this year the UK has lost 67 troops in Afghanistan, which is a little under one third of the 210 US fatalities over the same period. Military experts have warned that UK casualties are disproportionately high because Britain has only one tenth the number of troops in Afghanistan that the US does. Moreover, there are growing fears that public opinion in the UK, which is hostile to the war, might become increasingly negative in the months ahead. The Netherlands and Canada are both due to withdraw their troops over the next year, while Poland has indicated it wants to leave by 2012, three years before the 2015 deadline recently set by David Cameron. Britain will concentrate on the centre of Helmand, leaving the north and south to the US. It is understood that the redeployment was discussed by Mr Cameron and US president Barack Obama when they held a bilateral meeting in Toronto on the margins of the G20 summit. A senior British commander told the FT on Tuesday night: The plan to be unveiled puts all of the Upper Helmand Valley under the US and allows us to reinvest over 1,000 additional troops in Central Helmand, our main effort. While it is good to hand over Sangin, it also makes good tactical sense. All UK troops now come under British command in the most important area of Helmand, and this also helps US efforts [against the Taliban] in the town of Marjeh.(The Financial Times)