Radiation levels in seawater close to Japan’s quake-hit nuclear plant are more than 1,000 times higher than the safety limit, according to officials.
Some of the radioactive water has leaked into three of the Fukushima plant’s six reactors and engineers are frantically trying to pump it out.
Prime Minister Naoto Kan said the “situation is still very unpredictable and that “we need to continue to be extremely vigilant.”
Meanwhile, two Japanese tourists in China who were thought to have had high levels of radiation have been discharged from hospital.
The death toll from the earthquake and tsunami has passed 10,000. More than 17,000 people are still missing.