YUZHNO-SAKHALINSK, February 1 (RIA Novosti) - Four Japanese captains arrested for illegally fishing in Russian waters have been handed over to Japan, a border guard spokesman said on Friday.

On December 13, Russian border guards detained four Japanese fishing vessels for poaching near Russia's South Kuril Islands, a former Japanese territory.

"A Japanese vessel entered Russia's Exclusive Economic Zone, where it was met by border guards, who delivered the captains on board," the spokesman said.

The representative said the fishing vessels would remain under arrest in the Shikotan Island port.

On January 16, a Russian court found the four captains guilty of border violations, and sentenced them to a fine of 100,000 rubles ($4,117)

Confrontations over poaching between Russian authorities and Japanese fishing vessels are frequent in Russia's Pacific waters. In August 2006, a Japanese fisherman was shot dead near the Kuril Islands when Russian border guards opened fire at his boat after it refused to stop.

Russia and Japan have contested the ownership of the Kuril Islands for over 60 years, a dispute that has kept the two countries from signing a formal peace treaty after World War II.