The machines began the non-stop race on a 100-metre (109-yard) indoor track in the western city of Osaka after doing knee bends or raising their hands to greet spectators.

The bipedal robots, the tallest of which measures 44 centimetres (17.6 inches) must complete 423 laps to reach their goal.

The "Robo Mara Full" race is organised by Vstone Co., a robot technology firm based in the western industrial city, in cooperation with the Osaka prefectural government.

Competitors are allowed to change batteries and the so-called servomotors which control the robots' speed and other functions.