Sadiq Khan, Britain's Labour Party candidate for Mayor of London, delivers a speech in London May 3, 2016. [Photo/Agencies]

LONDON - Sadiq Khan of Britain's opposition Labour Party is the strong favourite to win London's mayoral election on Thursday after a contest marked by religious tensions and accusations of racism.

Polls show Khan, the son of a bus driver, is as much as 20 percentage points ahead of rival Conservative Zac Goldsmith in the race to run one of the world's top financial centres. If he wins, he will succeed current Conservative mayor Boris Johnson to become the first Muslim to head a major Western capital.

London's population of 8.6 million is among the most diverse and it is rare for identity politics to enter British campaigning.

Former human rights lawyer Khan says he has fought extremism all his life and regrets sharing a stage with speakers who held "abhorrent" views.

He has accused Goldsmith, the elite-educated son of a billionaire financier, of using Donald Trump-style tactics to divide Londoners along faith lines, as well as being part of an out-of-touch wealthy elite.