The government is considering inviting Russian President Vladimir Putin to visit Japan in December as part of efforts to make progress on a long-standing territorial row, government sources said.

To pave the way, the government wants to send Foreign Minister Fumio Kishida to Russia in September, the sources said. Putin and Prime Minister Shinzo Abe agreed last November in Beijing to begin preparations for Putin to visit Japan at a "suitable time" this year.

One source said Tuesday the government is looking at December because diplomatic schedules make it impossible to arrange an earlier visit, while other sources said time is needed to negotiate with Russia to realize Putin's visit and to gain U.S. acceptance.