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Robots running a full-length marathon in Japan

24 February 2011 Last updated at 10:59 GMT

Mini-robots are competing in the world's first robot marathon - Robo Mara Full race - in Osaka, Japan.

Five battery-charged machines are to complete 422 laps around an indoor 100-metre track in Osaka's Asia Pacific Trade Centre, covering 26 miles (42km).

The marathon is expected to continue until Sunday.