A Japanese court has halted the reactivating of the controversial Monju nuclear plant, shut down in 1995 following a serious sodium leak.

Nuclear campaigners said that the court's decision was a major blow to the government's nuclear programme.

The government was keen to revive the plant and develop it as a 'fast-breeder' reactor.

But high court judge Kazuo Kawasaki told the court: "We cannot deny the obvious danger of the release of radioactive substances".

We cannot deny the obvious danger of the release of radioactive substances. Judge Kazuo Kawasaki

He said it would be "a serious breach of the law" if the government was allowed to reactivate the plant, which is located 350 kilometres west of Tokyo.

Fast breeder systems are experimental reactors that produce more fuel than they use.

Although favoured by the Japanese government, they are technologically complex and unpopular with anti-nuclear campaigners.

Major victory

Local residents who brought the case to court welcomed the ruling.

Aileen Mioko Smith, an activist who has been campaigning on the issue for many years, said that this was an "epoch-making decision".

Japanese nuclear accidents

1995 Monju: major sodium leak July 1999 Tsuruga: internal radiation leak at 11,500 times the safety level Sept 1999 Tokaimura: Japan's worst nuclear accident, killed two and injured 40

She said that it was a very significant strike at "the whole raison d'etre" of the Japanese nuclear industry.

She also said that it was "indicative of societal change within Japan, as 'people power' was beginning to fight back against the status quo".

However, Atsuko Toyama, the Science and Technology Minister said the ruling was: "extremely regrettable" .

Nuclear needs

With few natural resources, Japan relies heavily on its 51 nuclear power plants to supply about a third of its' electricity.

By the year 2010, Japan was planning to raise that to 42% of its energy needs

Fast-breeder reactors were central to that plan.

But with public fears unallayed since an accident at Tokaimura in 1999, the government faces many hurdles in its plans for nuclear growth.