The Japanese government will urge Russia to exercise restraint as Moscow steps up measures over four Russian-held islands claimed by Japan.

Moscow's moves come as Japan imposes sanctions on the country for its invasion of Ukraine.
The sanctions include freezing assets of Russian President Vladimir Putin, government officials and financial institutions.

On Thursday, the Russian defense ministry announced that it had conducted a drill on the islands with a surface-to-air missile system.

Moscow also decided on Wednesday to exempt companies certified by the Russian government from corporate and other key taxes when doing business on what it calls the Kuril Islands, which include the four islands.

Japan calls the four islands the Northern Territories. The Japanese government maintains they are an inherent part of Japan's territory. It says the islands were illegally occupied after World War Two.

Last Monday, Russia included Japan in its list of countries and regions that have taken "unfriendly" action against Moscow.

Japanese Prime Minister Kishida Fumio indicated on Saturday that Japan will consider concrete steps for additional sanctions in coordination with other Group of Seven nations.

The Japanese government plans to call for Russia's restraint through diplomatic channels.