Tokyo police arrested the president of a ship-dealing company and his three associates Saturday on suspicion of exporting a secondhand fishing boat to North Korea without government approval. Police suspect the firm has illegally exported ships to North Korea in the past and that some of them may have been modified into spy ships, which have intruded into Japanese territorial waters.

Yoji Kishimoto, 59, president of Matsushima Kaiun, based in Tagajo, Miyagi Prefecture, and his three associates are suspected of violating the Foreign Exchange and Foreign Trade Control Law and forging documents.

The three others are: Yun Kyong Jung, 51, a ship broker based in Pusan, South Korea; Jumpei Maeda, 67, also a ship dealer; and Hiraku Sato, 34, a Matsushima Kaiun employee.

Police said the four conspired to illegally export the secondhand vessel to the North in June 2000 without approval from the trade minister. They applied for export approval on the pretense of selling the boat to an Indonesian fisheries company and received approval from the then Ministry of International Trade and Industry.

The squid boat, which was based in a fishing port in Fukushima Prefecture, was purchased from its owner for more than 10 million yen.

Earlier Saturday, staff from the Public Security Bureau of the Metropolitan Police Department raided the headquarters of Matsushima Kaiun.

In March 1999, two unidentified ships believed to be North Korean spy boats disguised as fishing vessels entered Japanese territorial waters off the Noto Peninsula in the Sea of Japan.

The two escaped pursuit by the Japan Coast Guard and Maritime Self-Defense Force after refusing to stop despite repeated warning shots from patrol boats and bombs dropped nearby by patrol planes.

Set up in 1992, Matsushima Kaiun exports used fishing boats, mainly to China, South Korea and the Philippines.