The machine can also carry a small wired vehicle equipped with a camera and send it out to crawl into small spaces to carry out inspections.

Toshiba engineer Goro Yanase said the as-yet unnamed robot could be upgraded to carry more than 80 kilograms, climb ladders and step over obstacles up to 50 centimetres (20 inches) high.

Robots have already been used inside the wrecked plant to take video footage, including the US-made PackBot and Japanese-made Quince crawler robots, but Toshiba is awaiting the go ahead from plant operator TEPCO to deploy its creation.

The massive earthquake and tsunami of March 11 last year sparked an atomic emergency at the Fukushima Daiichi plant in the northeast of the country.

Efforts to clear up after the worst nuclear disaster since Chernobyl in 1986 are still continuing, with high levels of radiation hampering operations.

The decommissioning of the crippled plant is expected to take several decades.