THE first comprehensive data testing by US nuclear scientists shows radioactive contamination has spread within the 30km Fukushima exclusion zone.

Spent fuel rods are now almost completely exposed, while footage released yesterday shows the damage from explosions at the plant is worse than thought.

Workers at the plant, the so called Fukushima Fifty, continue to fight to bring down the temperature of the overheating fuel rods, while aircraft and fire trucks douse the plant with water.

Officials are also racing to restore power to the site, prompting criticisms these steps should have been taken days ago, when the crisis was in its early stages.

The head of the United Nation's International Atomic Energy Agency, Yukiya Amano, has arrived in Tokyo and described the crisis as "an extremely serious accident".

"This is not something that just Japan should deal with - people of the entire world should co-operate with Japan," he said.

The data shows harmful radiation in the immediate vicinity of the plant. with AGENCIES

Originally published as Radiation spreading in exclusion zone