Radiation leaks from a damaged nuclear power plant in tsunami-hit Japan now pose a risk to human health, officials have warned.
Concerns rose for those near Fukushima Dai-ichi plant as a third explosion rocked the complex early this morning.
The nuclear crisis deepened as the official death toll topped 2,400 following the 9.0-magnitude quake and tsunami on Friday.
Tens of thousands are still missing, and there are fears some Britons may be among the dead.
In a televised statement after the latest blast, believed to be in the number 2 reactor, prime minister Naoto Kan urged those within 30km of the area to stay indoors.
Mr Kan said: "The level seems very high, and there is still a very high risk of more radiation coming out."
In addition to the three blasts that have occurred since Saturday, chief cabinet secretary Yukio Edano said a fire had broken out in a fourth reactor at the plant, and more radiation had been released.
Mr Edano said: "Now we are talking about levels that can damage human health. These are readings taken near the area where we believe the releases are happening. Far away, the levels should be lower.
"Please do not go outside. Please stay indoors. Please close windows and make your homes airtight. Don't turn on ventilators. Please hang on your laundry indoors.
"These are figures that potentially affect health, there is no mistake about that."
Some 800 non-essential staff have been evacuated from the plant, while 50 workers remained at the complex to try to cool the reactors with water.
© Press Association