London Marathon: Doping files suggest results are in question
The London Marathon was won seven times in 12 years by athletes who have recorded suspicious blood scores, according to the Sunday Times.
The tally represents nearly 30% of winners in the 24 men's and women's races.
Last week the newspaper - along with German broadcaster ARD - revealed details from a leak of 12000 blood test results from 5000 athletes.
The latest revelations focus on what the Sunday Times calls "the alarming extent of suspected cheating by elite athletes in the six mass public marathons around the world."
London, Boston, Chicago, New York, Berlin and Tokyo are the races to which they refer.
Based on "an expert analysis", the newspaper claims:
The winners of 34 major city marathons - one in four - "should have faced censure or at least been investigated over evidence of potential blood doping within their test results."
Athletes whose results were considered suspicious by the Sunday Times's experts collected more than £4m in prize money from those marathons.
In London, seven wins, six second places and seven third places were secured by "athletes whose blood tests were deemed suspicious by the experts".
Russian Liliya Shobukhova won the 2010 London Marathon and has had her results since 2009 annulled