MOSCOW--Russia has established high-speed Internet service on a chain of Pacific islands off its far eastern coast, state-run telecoms operator Rostelecom said on Tuesday, despite a decades-old dispute with Japan over the territory.

Rostelecom said an 815-kilometer fiber optic cable line had been laid between Russia's offshore Sakhalin island and the island chain to introduce fast Internet in four towns and villages on the islands that it calls Iturup, Kunashir and Shikotan.

Russia and Japan both claim sovereignty over the chain of four islands--known as the Northern Territories in Japan and the Southern Kuriles in Russia--which were captured by Soviet troops during the final days of World War II.

Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe hold regular talks to resolve the protracted dispute, which has prevented Moscow and Tokyo from formally ending hostilities from the war.

The fiber optic project cost 3.3 billion roubles ($50.30 million or 5.5 billion yen), most of which came from the Russian state budget, according to Rostelecom.

The project looked like another sign that despite ongoing talks with Japan, Moscow is loath to cede the islands.

In December, Russia said it had built new barracks to house its troops on the islands and would construct more facilities for armored vehicles.

Russian energy giant Gazprom also plans to build a liquefied natural gas plant on Sakhalin to supply the island chain.