The Afghan president, Hamid Karzai, has questioned whether western troops were "fighting in the wrong place" during their decade-long mission in Afghanistan, saying security was better in southern Helmand province before the arrival of British forces.

Karzai said he was unclear if western forces were leaving Afghanistan because they felt they had achieved the aim of making their own countries more secure by tackling international terror groups - or because they had realised the mission was mistaken.

In an interview ahead of trilateral talks with British prime minister, David Cameron, and the Pakistani president, Asif Ali Zardari, Karzai said the greatest long-term threat to the country was not the insurgents but meddling by foreign powers.

He did not name Pakistan, but he has long been a critic of the neighbouring country, and his government has accused Islamabad's military intelligence of manipulating the insurgents.