Japanese Prime Minister Yoshihide Suga and Russian President Vladimir Putin are planning to hold their first talks on Tuesday after the premier took office last week to succeed Shinzo Abe, a Japanese government source said Saturday.

During the talks by phone, the two leaders are expected to reaffirm their countries' commitment to continuing bilateral negotiations toward signing a postwar peace treaty and the necessity for economic cooperation.

Japan and Russia have struggled to resolve a long-standing territorial dispute regarding Russian-held isles off Hokkaido, called the Northern Territories in Japan and the Southern Kurils in Russia, and it has prevented them from signing a peace treaty.

Combined file photo shows Japanese Prime Minister Yoshihide Suga (L) and Russian President Vladimir Putin. (Kyodo)

The Soviet Union seized the islands following Japan's surrender in World War II in 1945. Moscow says it acquired them as a legitimate outcome of the war, while Tokyo argues their seizure was illegal.

The two countries have agreed to carry out joint economic projects on the islands as a trust-building exercise while they work toward a mutually acceptable resolution.

After announcing in late August his decision to resign due to health problems, then Prime Minister Shinzo Abe spoke with Putin in a teleconference and the two emphasized the need to resolve the issue.

Since he was elected as prime minister on Sept. 16, Suga has been holding phone talks with various global leaders, including from the United States, China, South Korea and India.

He has raised the issue of North Korea's abductions of Japanese nationals in the 1970s and 1980s during each phone conversation and requested cooperation in resolving it, Chief Cabinet Secretary Katsunobu Kato said during a press conference Thursday.

Suga is also planning on holding talks with French President Emmanuel Macron, according to government sources.

Suga may meet with U.S. Secretary of State Mike Pompeo when he visits Tokyo for a gathering of foreign ministers of Japan, Australia and India that is now being arranged for October.

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