Reports from Japan say the country has raised the alert level at a stricken nuclear plant from four to five on a seven-point international scale for atomic incidents.The crisis at the Fukushima Daiichi site is now two levels below Ukraine’s 1986 Chernobyl disaster.
The head of the UN’s nuclear watchdog warned in Tokyo the battle to stabilise the plant was a race against time.
The crisis was prompted by last week’s huge quake and tsunami, which left more than 16,000 people dead or missing.
The Japanese nuclear agency’s decision to raise the alert level to five grades Fukushima’s as an “accident with wider consequences”.
Meanwhile, further heavy snowfall overnight brought more misery to survivors of the 9.0-magnitude quake and tsunami, all but ending hopes of finding anyone else alive in the rubble.
According to the latest figures, 6,405 people are confirmed dead and about 10,200 are listed missing.
The head of the International Atomic Energy Agency, Yukiya Amano, arrived in Tokyo and said the Fukushima crisis was a “race against the clock”.
“This is not something that just Japan should deal with, and people of the entire world should co-operate with Japan and the people in the disaster areas,” said Mr Amano, a Japanese citizen.