The Japanese government is attempting to contain what it says is the worst nuclear accident in the country's history, after a serious radiation leak in a uranium processing plant.

Fourteen workers have been taken to hospital -- two of them in a critical condition -- and more than three-hundred thousand people living nearby are being told to stay indoors.

The site of the emergency is in the town of Tokaimura, just over a hundred kilometres 70 miles north of Tokyo.

Reports say the accident happened after workers at the plant set off an atomic reaction by pouring too much uranium solution into a tank.

The Japanese prime minister, Keizo Obuchi, has taken charge of a special task force.

He criticised what he said was the slow response to the accident.

It's been announced in Washington that a joint American and Russian team is being sent to Japan.