Foreign Minister Toshimitsu Motegi has proposed "concrete steps" to Russian counterpart, Sergey Lavrov, to resolve a long-standing territorial dispute, the minister has said.

Motegi did not say what the steps were, but told reporters he invited Lavrov to visit Japan soon to continue negotiations aimed at resolving the dispute, which remains a hurdle to signing a postwar peace treaty.

The two spoke for about 50 minutes on the fringes of an annual security conference in the German city of Munich.

The territorial dispute is over a group of islands off Hokkaido that were seized by Soviet troops following Japan's surrender in World War II. Tokyo has demanded their return, arguing that Moscow's actions violated international law. Russia maintains that their seizure was a legitimate outcome of the war.

Motegi told reporters Saturday that he and Lavrov explored solutions that would be acceptable to both countries, adding that negotiations had "entered a new phase."

Prime Minister Shinzo Abe has been focusing on the return of the smaller two of the four disputed islands, an arrangement that was mentioned in a 1956 joint statement. But the plan stalled, with Russian President Vladimir Putin having taken a more hard-line stance on the issue.

In the meantime, the countries have agreed to carry out joint economic projects in five fields — aquaculture, greenhouse farming, tourism, wind power and waste reduction — on the islands as a trust-building measure.

Motegi and Lavrov discussed stepping up efforts to launch some of the projects in earnest this year, according to the Foreign Ministry in Tokyo.

Japan calls the islands the Northern Territories while Russia refers to them as the Southern Kurils.