"The Northern Territories are an inherent part of Japan's territory, and we cannot accept the move," a senior ministry official also said, a day after Russia announced its military began military exercises on the Russia-held, Japan-claimed islands.
The official said Japan has confirmed that Russia conducted drills on two of the four islands - Etorofu and Kunashiri. Tokyo had urged Moscow through diplomatic channels to cancel the drills after learning of the Russian military's move by Aug. 5, the official added.
The spat over the Northern Territories, which also include Shikotan, and the Habomai islet group, has prevented Tokyo and Russia from signing a peace treaty. The islands, called the Southern Kurils in Russia, were seized by the Soviet Union following Japan's surrender in World War II on Aug. 15, 1945.
Abe has been trying to resolve the dispute by building a personal relationship of trust with Russian President Vladimir Putin, who has been under international pressure since Moscow's annexation of Crimea.
Kyodo