HIGHLY radioactive water from Japan's crippled Fukushima nuclear plant is pouring out at a rate of 300 tonnes a day, officials have revealed, as Prime Minister Shinzo Abe ordered the government to step in and help with the clean-up.

The admission indicates that, two-and-a-half years after the plant was hit by a huge earthquake and tsunami, plant operator Tokyo Electric Power Co (Tepco), which only recently admitted any water had leaked, has yet come to grips with the worst nuclear disaster since Chernobyl.

Calling water containment at the Fukushima Daiichi station an "urgent issue," Mr Abe ordered the government for the first time to get involved to help struggling Tepco handle the crisis.

The newly acknowledged leak from the plant, 130 miles north-east of Tokyo, is enough to fill an Olympic swimming pool in barely a week. The water is spilling into the Pacific Ocean, but it was not immediately clear how much of a threat it poses.

Mr Abe said: "The contaminated water problem is one that the Japanese people have a high level of interest in and is an urgent issue to deal with."

The Japanese leader stopped short of pledging funds to deal with the issue, which could take billions of pounds to clear up, but ministers have requested a budget allocation to help address the water problem.

Government nuclear official Tatsuya Shinkawa said it was believed water had been leaking for two years.