PRIME Minister Gordon Brown will today issue a vigorous defence of Britain’s military mission in Afghanistan, as he repeats warnings that the al-Qaida terror network poses the biggest source of threat to UK national security.

He will say that action against al-Qaida has had greater impact this year than in any 12-month period since the 2001 war to topple the Taliban, but will warn that the terror group continues to recruit and train and could return to Afghanistan if international forces pulled out.

The comments, in his annual Guildhall foreign policy speech, mark the latest stage in the Prime Minister’s drive to shore up public support for the war, following a radio interview, a speech to military top brass and an address to the Commons in recent weeks.

They come a day after a poll suggesting that almost three-quarters of voters (71%) want British troops withdrawn from Afghanistan within a year. And they follow the death yesterday of the 96th British serviceman to be killed in Afghanistan this year, a soldier from 7th Battalion The Rifles who was shot while on foot patrol near Sangin in Helmand province.

Speaking at the Lord Mayor of London’s Banquet, Mr Brown will reject an approach of “splendid isolation” and say that Britain needs a foreign policy that is both “patriotic and internationalist”.