As of the end of January, 642 Japanese had registered their legal addresses as isles subject to territorial disputes with neighboring countries, despite living elsewhere, a Kyodo News survey of municipalities found Tuesday.

The number of such registrations in a January 2011 survey by Kyodo reached about 520. The recent rise apparently reflects heightened tensions between Japan and China, South Korea and Russia over contested territories.

Japanese citizens are allowed to register any place claimed by Japan as their legal residence, even if they do not actually live there, as long as the place in question has a land number allocated by domestic authorities.

There were 196 Japanese who registered as their official domiciles the four Russian-administered islands off Hokkaido — Etorofu, Kunashiri, Shikotan and the Habomai islets — up from 175 in 2011, according to Nemuro, the Hokkaido municipality that nominally includes the islands.

The town of Okinoshima in Shimane Prefecture said 102 Japanese have registered their address as Takeshima, a pair of South Korea-controlled islets in the Sea of Japan, up from 69 in the previous survey.

An Okinoshima official said the number of inquiries about transferring official domiciles to Takeshima jumped to about 20 a week, after an unprecedented visit to the islets last August by then-South Korean President Lee Myung Bak.

A 49-year-old former secretary of a Diet member, who changed his address to Takeshima in 1996, said he talks about the disputed islets more often than before and noted people are often surprised to see that address written on his driver’s license.

Sixty-three Japanese registered the Japan-controlled Senkaku Islands in the East China Sea as their addresses, according to the Okinawa city of Ishigaki, up from about 20 in 2011.

Another 281 have changed their official addresses to Okinotori, the nation’s southernmost point, up from 262 in 2011, according to the village of Ogasawara in the Ogasawara Islands south of Tokyo.

China maintains that Okinotori is not an island but a group of rocks and opposes Japan’s claim to a 200-nautical-mile exclusive economic zone around the atoll, which is located about 1,740 km south of Tokyo.

Yoshihiko Yamada, a professor of marine policy at Tokai University and an expert on the nation’s territorial disputes, said the change in official addresses was “obviously triggered by rows” over the contested islands.

No leeway on Senkakus

Japan remains firm in its sovereignty claim over the Senkaku Islands, a government spokesman said Tuesday in response to China’s remarks the previous day aimed at justifying the presence of Chinese patrol vessels near the islets.

“Japan cannot accept any remarks by China concerning the Senkaku Islands that are based on a unilateral claim,” Deputy Chief Cabinet Secretary Hiroshige Seko said. “It is obvious the islands are inherent Japanese territory both historically and under international law.”

China claims the two nations reached such an understanding during bilateral negotiations on normalizing diplomatic relations in 1972, but Japan says such an agreement has never existed.