London: British Foreign Secretary David Miliband, seen as a possible successor to struggling Prime Minister Gordon Brown, has warned the ruling Labour party to stop fighting amongst itself - or risk poll defeat.

Brown is under fire over his decision to scrap a 10pence tax band and over plans to extend the period terror suspects can be held without charge.

Writing in the News of the World, Miliband warned the party was now the "political underdog".

Brown's popularity has plunged since he took office last year over fears he cannot manage an economic downturn despite a successful decade as finance minister. His party now risks a drubbing in local elections on May 1 and also losing power to the opposition Conservatives in general elections which are due by mid-2010.