Former Prime Minister Yoshiro Mori is arranging to visit Russia for talks with President Vladimir Putin on Sunday, a diplomatic source said Wednesday.

The planned three-day visit to Russia, starting Saturday, is aimed at supporting Prime Minister Shinzo Abe, who is eager to settle a decades-old dispute over islands off Hokkaido that are controlled by Russia but claimed by Japan, the source said.

Mori has maintained friendly ties with Putin since he was prime minister for a year through April 2001.

He is planning to meet with Putin in the city of Yekaterinburg in the Ural Mountains, just after Abe and the Russian leader are scheduled to hold talks Friday on the sidelines of the Group of 20 summit in Hamburg, Germany, the source said.

The islands of Etorofu, Kunashiri, Shikotan and the Habomai islet group were seized by the Soviet Union after Japan surrendered at the end of World War II in August 1945.

They are called the Southern Kurils in Russia and the Northern Territories in Japan.

The long-running dispute has prevented the countries from signing a postwar peace treaty.

Tokyo and Moscow have just conducted their first study on potential joint economic activities on the islands. During the envisioned meeting, Mori plans to urge Putin to accelerate discussions over joint economic activities, according to the source.

Mori is also expected to explain Japan's stance on the disputed islands to allay Putin's concerns that U.S. military forces could be stationed on them if they are returned to Tokyo.

In an interview with media outlets last month, Putin expressed such concerns and said that Russia's military buildup on the islands is aimed at countering the United States.