The personal data of 38,000 runners in the London Marathon were accidentally published on the organiser’s website.
A BBC report revealed that the details of runners – including addresses – were available on the website all day on Monday 23 April 2012. The thousands of runners included many celebrities.
The organisers were not aware of the problem until the BBC alerted them, after a television presenter was contacted by a member of the public who had found her home address.
Nick Bitel, CEO of the London Marathon, told the BBC: "We immediately made sure the glitch was corrected.
"We do not believe this has led to a substantial number of individuals' details being accessed by members of the public."
The Information Commissioners Office (ICO) said: “We’re aware of a possible data breach involving the website of the organisers of the London Marathon. We will be investigating this, before deciding what action, if any, needs to be taken.”