British American Tobacco is facing an investigation by the World Health Organisation (WHO) into allegations that the company is putting sugar and honey into cigarettes in a bid to woo under-age smokers.

The new probe into BAT, disclosed to the Times by WHO's tobacco unit, is billed as a "yet another embarrassment" to Tory leadership contender and former health secretary, Kenneth Clarke.

Clarke dismissed the latest claims saying it "is one of the oldest controversies in the arguments about tobacco that I can recall".

"It has absolutely nothing with me as non-executive deputy chairman of a British company," he said.