President Vladimir Putin's plan to visit Japan in the fall remains unchanged, Foreign Minister Sergey Lavrov said Monday, dismissing views the trip has been jeopardized by the Ukraine crisis.

"We've accepted Japan's invitation and Japan has also set the period for the visit," Lavrov said during a news conference, calling information other than that "groundless."

His remark, coming amid growing doubts in Japan that the trip will come off as planned, suggests Russia doesn't intend to call off the visit unless Japan retracts its invitation.

Earlier this month, Japan imposed additional sanctions on Russia for its infringement of Ukrainian sovereignty through continued support of pro-Russian separatists by freezing assets held in Japan by 40 individuals and two groups directly involved in Russia's annexation of Crimea and the instability in eastern Ukraine.

Lavrov said his country's relations with Japan are "not associated with the conflict in Ukraine."

Putin and Prime Minister Shinzo Abe agreed in February that Putin would visit Japan in the fall.

Tokyo has characterized the visit as a way to advance negotiations for the return of the four Russian-held islands off Hokkaido.

The row over the islets — Etorofu, Kunashiri, Shikotan and the Habomai islet group — has prevented Tokyo and Moscow from concluding a postwar peace treaty.