The political challenge Gordon Brown would face if he agrees to send more troops to Afghanistan next year has been highlighted in an opinion poll which shows that 68 per cent of Britons believe the UK should withdraw within 12 months.

As Hamid Karzai, the Afghan president, arrived in London yesterday on a mission to persuade Mr Brown, prime minister, to send military reinforcements to his country, the BBC poll showed that only 24 per cent of people believed UK troops should stay, while 8 per cent said they had no view on the matter.