America is planning to send at least 5,000 additional troops to Afghanistan's Helmand province to help out beleaguered British troops, according to defence sources in Washington and Kabul.

Ministers are expected to examine early next year whether British reinforcements will also be sent to boost the present force of 8,100 troops in the British-controlled province.

The planned near-doubling of coalition forces in Helmand could, however, ease pressure to increase British force levels. London has made clear it does not plan to transfer the 3,700 troops coming out of Iraq next summer straight into Helmand.

General David McKiernan, the American commander of Nato's International Security Assistance Force (Isaf) and the US Operation Enduring Freedom, admitted yesterday that the battles with the Taleban in Helmand and elsewhere in southern Afghanistan had run into a tactical stalemate, despite attritional attacks against insurgency leaders.

The Americans are planning to send three combat brigades of at least 20,000 extra troops to Afghanistan from January. Some estimates coming out of Washington suggest that the total could be as high as 30,000. Although it is being called a surge, like the US reinforcement of Iraq, the British refer to it as an “uplift” because the additional troops will remain for the long term.

Under current planning, 5,000 will go to Helmand, another 5,000 will be based in neighbouring Kandahar, and also in Zabul and Oruzgan provinces in the south, and the remainder will be sent to eastern Afghanistan. If Barack Obama approves the option to send another 30,000 troops when he becomes President next month, it will nearly double the American presence in Afghanistan from 32,000 to 62,000.

The decision to send 5,000 to Helmand will lead to a restructuring of the forces in the province, with control being split between the British in the north and the US in the south.

In the two years since British troops arrived in force in Helmand, there has been fierce fighting with the Taleban, but despite some notable successes, the insurgents have remained resilient. Some American military figures have complained that the British have failed to take the fight to the Taleban, but during the campaign, codenamed Operation Herrick, Britain's commanders have tried to mix offensive action with hearts-and-minds missions among the tribal elders and local people to persuade them against supporting the Taleban.

Military commanders admit that the past 12 months have been tough for the British troops, with a rising number of roadside-bomb attacks. Britain will be intimately involved in the command and control of the American forces in Helmand and elsewhere in the south because next year a British commander, Major-General Nick Carter, is to take charge of Regional Command South, one of the key headquarters set up by Isaf.

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