Russia has denied claims of being involved in spying following the arrest of a 52-year-old Japanese official accused of leaking information.

The member of Japan's Cabinet Information Research Office, whose name has not been released, is accused of supplying classified information on the country's political policy to Russian Embassy officials.

The Prime Minister of Japan says tough measures should be taken if the allegations are proved.

Sergey Yasenev, spokesman of the Russian Embassy in Japan, said it's somebody's attempt to compromise Russia in Japan's eyes.

“Obviously not everybody in Japan is happy with the positive process that is taking place in Russian-Japanese relations. The ties between our two countries are developing dynamically in a number of areas. Apparently not everybody in Japan likes to see it. That is why they are trying to compromise Russia,” said Sergey Yasenev.