Defence chiefs are making contingency plans to send 3,000 extra troops to southern Afghanistan next year as part of a US-led surge.

The troops, a mixture of regular infantry, engineers, artillery and special forces are needed to counter growing Taliban activity across Helmand province.

The plans for an increase – expected to be temporary – have not been given the go-ahead by Gordon Brown. However, the Ministry of Defence has prepared them in anticipation of an American request for more troops when Barack Obama, the president-elect, speaks to Brown after his inauguration in January.

Admiral Mike Mullen, chairman of the joint chiefs of staff, said yesterday in Kabul that up to 30,000 American troops could be sent to Afghanistan by next summer.

The Americans had previously said they would dispatch an additional 5,000 soldiers to the southern province where they already have 2,400 marines, with more expected to follow. They will significantly outnumber the 5,000 British troops in the province, raising a question over the UK’s control over Helmand and its own troops.

Brown announced last week that 270 additional troops had been ordered to Helmand to help to put down a growing insurgency in the Nad-e-Ali area that is threatening Lashkar Gah, the nearby provincial capital. They will be replaced in March. General John Craddock, Nato’s supreme allied commander Europe, said last week that such small numbers would not “do the trick” in Helmand.

Senior officers said the 270 troops came from a reserve based in Cyprus but were almost permanently deployed in Afghanistan because of the ferocity of the Taliban insurgency. Britain did not have enough troops in Helmand, the officers said. Although there are more than 8,000 troops in Afghanistan, only 5,000 are in Helmand, which is roughly the size of Switzerland.

Three British battle groups are operating there but commanders say their numbers are too few to clear out insurgents.

“The Taliban control half of Helmand,” one senior officer said. “We can force them out of anywhere but we don’t have enough troops to hold the ground, so when we leave they come back.”

All requests for reinforcements have been refused until now because of the continuing commitment of 4,100 troops in Iraq.

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