A former Mexican presidential candidate who was disqualified from the Berlin marathon for cheating says he is innocent and is blaming political mudslinging for the scandal. Roberto Madrazo is a veteran of 36 marathons who played up his running-man credentials in the 2006 election campaign.

Sporting a bright-red jacket, the 55-year-old politician was photographed with his arms aloft and beaming after he broke through the finish line in first place for his age group.

But race organisers later stripped him of the title after finding he did not run a nine-mile stretch of the course.

Madrazo said he had always wanted to run the five most important marathons - Boston, New York, Chicago, London and Berlin - and only the German city was missing on his list but he was carrying an injury.

"I had to stop after 21 km and I went directly to the finish line for my clothes and my medal for taking part," he said. "In sport there are no short-cuts, there are personal challenges."

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