The patrolling and security units would be posted at a total of 90 places facing the Sea of Japan (East Sea) and equipped with radars to detect approaching spy ships and submarines, Jiji Press news agency said.

They would tackle spies and guerrillas upon their landing on Japanese soil, it said without specifying sources.

The Defence Agency decided where to deploy these forces by analysing past cases of North Korean agents' sneaking into Japan, it said.

Besides the spots North Koreans might use to enter Japan, the agency picked areas with nuclear power plants, petrochemical complexes and other important facilities that might be the target of terror attacks, it said.

Priority areas would include Wakasa Bay areas in central Japan where nuclear power plants are clustered, the news agency said, adding Japan planned to deploy some 200 personnel there.

North Korean agents here are believed to have engaged in activities ranging from kidnapping of Japanese citizens for training spies in Japanese language and culture to smuggling of high-tech electronics for weapons development.

Under the Defence Agency's deployment, Japanese navy forces would be able to repel 80 percent of North Korean attempts to sneak into Japan, Jiji Press said.

But the remaining 20 percent would manage to reach the Japanese coast, it said.

No immediate comment was available from the defence agency.