NHK has learned that Russia notified Japan it cannot hold annual talks this year that are aimed at ensuring the safety of Japanese fishing boats when they operate near the four Russian-held islands claimed by Japan.

The Japanese embassy in Moscow says it received a unilateral notification from Russia's foreign ministry on Thursday.

The annual talks are based on an agreement the two countries' governments made in 1998. It safeguards fishery workers operating in waters near the islands from being detained by Russian authorities.

Russia controls the islands. Japan claims them. The Japanese government maintains the islands are an inherent part of Japan's territory. It says the islands were illegally occupied after World War Two.

The governments have negotiated each year to decide the fishing period, size of catches and amount of money the Japanese side pays.

The agreement mainly covers walleye pollack, Okhotsk atka mackerel and octopus. The fishing period usually starts as early as January.

Japanese embassy officials called Russia's move regrettable. They say they will strongly urge Moscow to start talks soon to allow fishing boats to begin operations as soon as possible in this season.

Moscow has included Japan in its list of "unfriendly" countries that are imposing sanctions on Russia in relation to its invasion of Ukraine. In March, Russia unilaterally announced that it was suspending peace treaty talks with Japan.