Japan’s radiation leak at Fukushima nuclear plant has been identified as a 20cm (8in) crack in the walls of a containment pit at Reactor 2.

Efforts have been made to plug the hole, but have so far been unsuccessful.

Chief Cabinet Secretary Yukio Edano said: “We need to stop the spread of (contaminated water) into the ocean as soon as possible. With that strong determination, we are asking Tokyo Electric Power Co (Tepco) to act quickly”.

Japan: Fukushima nuclear radiation reaches UK

Radiation leaking from Fukushima

He warned that long-term radiation from the leak would “have a huge impact on the ocean”.

Dye and salt is now used to trace the polluted water as it makes it way from the plant to the sea.

Tepco said it would once again try to inject a special polymer to try to stop the flow, as soon as they had been able to identify the path of the radiation leak.

Emergency workers at the nuclear plant are trying to decide whether to pump in more water into the reactors or not.

If they don’t, the reactors could overheat.

But more water being pumped into the reactor would also mean that more radioactive water could flow into the ocean.

The Nuclear and Industrial Safety Agency is considering building embankments as a temporary measure to stop the flow of water into the sea.