"The format will not change, it will just be modified but there will not be any radically new format [of talks]. The leaders will determine the individuals who will be directly engaged in energizing the process of the negotiations on the basis of the [Soviet-Japanese] declaration of 1956. The decision will be made now in Buenos Aires," the source said.
Japan and Russia have never signed a permanent peace treaty after the end of World War II due to the territorial dispute over a group of four islands that both countries claim — Iturup, Kunashir, Shikotan and Habomai — referred to as the Southern Kurils by Russia and the Northern Territories by Japan.
READ MORE: Russia, Japan Peace Treaty Talks Require Tokyo's Allied Obligations — Kremlin
The G20 summit will be held in Argentina on Friday and Saturday.
Apart from holding talks with Abe, Putin is expected to meet with the leaders of China, France and Germany during the forum.