Operation Mountain Fury involves some 3,000 troops US-led troops and 4,000 Afghan security personnel, the US said.

It aims to place "continuous pressure" on the Taleban in eastern provinces close to the border with Pakistan.

Nato-led forces in southern Afghanistan are also fighting the Taleban, but US troops are not under Nato command.

A spokesman for the US military said the new operation had been in preparation for weeks but entered an operational phase yesterday afternoon.

Troops fanned out in the eastern provinces of Paktika, Khost and Paktia, as well as in Ghazni and Logar provinces.

The troops are aiming to restore security as well as undertaking development and rebuilding projects, the military said.

The resurgent Taleban has seen international commanders in Afghanistan request more troops for the ongoing mission in the country.

The past year has been the most violent in Afghanistan since a US-led offensive toppled the Taleban government in 2001.

Fighting in the south and east has been intense, but the insurgency also includes assassinations, school burning and the use of roadside bombs.

Meanwhile, it was reported last night that Britain is considering sending extra troops to Afghanistan following Nato's failure to offer reinforcements requested by commanders attempting to combat a reinvigorated Taleban.

Contingency plans are being drawn up after commanders warned that lack of reinforcements for an autumn offensive would severely hinder the campaign momentum. The options for deployment under consideration include the current spearhead battalion, 2 Royal Scots (formerly the Royal Highland Fusiliers) on a short term basis, or either the 1st Battalion The Royal Irish Rangers or the 2nd Battalion The Parachute Regiment.

The Canadians, also taking losses in the Kandahar region, are reinforcing their contingents with troops as well as 15 Leopard tanks. Sending the troops, however, will not solve the problem of lack of helicopters, which has been dogging the Nato force. Land convoys are regularly ambushed, and even a routine re-supplying run now needs a full group battle group for protection. The British military are adamant there are no helicopters to spare.