Police in the Japanese port city of Niigata, said they found a home-made, bomb-like object and a bullet fired overnight at buildings related to the local branch of the pro-Pyongyang General Association of Korean Residents in Japan (Chongryon).

The discovery of the suspected explosive device outside a Chongryon-affiliated bank prompted the evacuation of some 160 families in the area for one hour, Niigata police said.

The device, a plastic container with wiring, was still being examined late Wednesday.

A few hours earlier, a bullet was found fired into the shutters at a warehouse at Chongryon's head office in Niigata.

"It is a case which directly threatens the lives and assets of Korean residents in Japan," Chongryon's head office in Tokyo said, adding it was apparently aimed at "spreading hostile sentiment against Chongryon and our republic."

Chongryon holds several seats in North Korea's national congress and acts on behalf of the Pyongyang regime in the absence of diplomatic ties with Tokyo.

Japanese have angrily reacted to North Korean leader Kim Jong-Il's admission last September that his country kidnapped Japanese nationals during the Cold War years to use them as spy tutors.

Pyongyang's nuclear arms programme has added fuel to their indignation and stalled talks on rapprochement with Tokyo which could bring economic relief to its moribund economy.

Niigata police had acted after the influential national newspaper Asahi Shimbun and the local daily Niigata Nippo received an identical call late Tuesday that a bullet has been shot at the office and a bomb has been set at the bank.

The call came from a group calling itself "Kenkoku Giyugun (nation-building voluntary army)" and warned that the action would continue "until Koreans are eradicated from Japan."

In recent months, the Chongryon office in Niigata has reportedly received theatening calls over the use of the port as the Japanese terminal of the only regular ferry route between the two countries.

The North Korean ferry Mangyong Bong-92 has cancelled visits to Niigata since June after Japan tightened checks on North Korean ships amid suspicions that some of them have been engaged in smuggling missile parts and drugs.

Last November, Chongryon's national headquarters here received a threatening letter with a 38-calibre Magnum bullet inside. A Chongryon-linked bank in Nagoya, central Japan, was fired at in January.

A group, calling itself "Chosen Seibatsutai (expedition against Korea)" claimed responsibity.

WAR.WIRE