Radiation alert in Japan

The government in Japan is warning that radiation from the quake-stricken Fukushima Daiichi nuclear plant has reached harmful levels.



The warning comes after the plant was rocked by a third blast, which appears to have damaged one of the reactors' containment systems for the first time.



If it is breached, there are fears of more serious radioactive leaks.



Officials have extended the danger zone, warning residents within 18 miles to evacuate or stay indoors.



The crisis was triggered by last Friday's 9.0-magnitude quake and tsunami in north-eastern Japan.



Meanwhile, Chief Cabinet Secretary Yukio Edano says the remaining two reactors at the plant are being monitored as they have begun overheating slightly.