The Japanese parliament has passed new legislation aimed at strengthening nuclear safety measures.

The government was widely criticised for lax supervision and a slow response to the country's worst nuclear accident in September.

In the accident at a uranium processing plant at Tokaimura, workers accidentally caused nuclear fission by mixing too much uranium solution in a steel bucket.

They were exposed to huge doses of radiation and more than 300,000 people in the surrounding area were placed in danger.

The upper house of parliament unanimously passed the legislation aimed at giving the central government a greater role during nuclear accidents. The lower house passed the legislation last month.

The new measures

Under the new law, the prime minister can declare a state of "nuclear emergency" when an accident occurs.

It will be the head of government's responsibility to immediately set up a crisis management centre to order evacuations and other safety measures during a major nuclear disaster.

Local authorities, which have previously had primary responsibility for instructing residents on safety measures, have long demanded that central government should play a more active role in such incidents.

The new legislation requires nuclear facility operators to immediately report any accidents to the prime minister, who can call on Japan's Self-Defence Forces if necessary.

The law also requires periodic inspections of nuclear fuel facilities, previously required only for nuclear power plants.

A government study published just after the accident said 15 out of 17 nuclear facilities in Japan had inadequate safety measures.

The study, by the Labour Ministry, said, in particular, that not enough individual health checks for radiation exposure were being carried out, despite being required by law.