Officials at the Fukushima Daiichi nuclear power station in Japan have shown an underground wall of ice they are building to stop radioactive water from leaking from the facility.

Tepco, the owner of the station, which is still crippled three years after an earthquake and tsunami set off nuclear meltdowns in the region, has been fighting a continuous battle to deal with hundreds of thousands of tonnes of contaminated water.

Nuclear analyst concerned over 'ice wall'

The utility company is planning to build a 1.4km underground wall of ice around four reactor buildings at Fukushima to prevent underground water from flowing in, and stop radioactive water seeping into the Pacific Ocean.

Experts have to flood the damaged reactors with huge amounts of water to keep them cool. That water then becomes radioactive.

Tepco said it had already tested the technique at the site, but ran into trouble when it failed to cool the earth enough to freeze it.

However, Akiro Ono, the plant's manager, said the latest effort to construct the ice wall was succeeding.

"The ice wall itself has been tested. And in those cases we've seen that the ground itself does freeze so I myself am not that worried that it will not go well," Ono said.

But as Al Jazeera's technology reporter Tarek Bazley reports, some experts say the project is flawed, and could create more problems than it solves.

John Large, a nuclear analyst, has said that keeping the ice wall as a long-term solution is too difficult because it requires constant powering.

He described it as a "short-term solution for a long-term initiative".