Britain must send more troops to Afghanistan to defeat Taliban, says military chief

Brigadier Mark Carleton-Smith said British forces were still on a 'growth trajectory'.

The commander of 16th Air Assault Brigade warned it could be five years before numbers could begin to drop in Helmand province.

Persuasion:  Brigadier Mark Carleton-Smith, with the PM this week during his visit to Afghanistan, also warned it could be five years before troop numbers drop

Military chiefs are understood to want to bolster the number of troops on the ground in Afghanistan's southern 'badlands' by 50 per cent, from about 8,000 to 12,000.

The reinforcement is expected to coincide with the predicted scaling-back of troops in Iraq within a year.

Brigadier Carleton-Smith, who has been in charge during a tour which has cost the lives of 24 UK servicemen and one woman, said: 'A characteristic of counter-insurgency is that the more successful you are the more troops you require.

'The more ground and the more people you become responsible for, the more troops you need.'

When Britain took over Helmand in 2006, the operation was expected to need only 3,300 troops on the ground. But senior Nato commanders have been calling for more.

Resurgent: The Taliban are growing stronger after losing power in 2001

The mounting dangers were underlined this week by the death of ten French troops in a Taliban ambush just 30 miles from Kabul. On Thursday, three Polish soldiers serving with Nato died in a roadside blast.

But Brigadier Carleton-Smith said he was 'cautiously optimistic' that coalition forces were dampening down the uprising.

U.S. forces were accused by the Afghan Foreign Ministry last night of killing 76 civilians, most of them children, in air strikes in Herat yesterday.

American commanders said the only casualties had been 30 insurgents.