Japan on Monday called for a peaceful resolution to the Ukraine crisis, but said a local referendum on whether Crimea should join Russia would be unconstitutional and call into question the territorial integrity of the Ukraine.
Chief Cabinet Secretary Yoshihide Suga called the referendum planned for March 16 unconstitutional, after the United States and other Western countries also rejected the move.
"We see (the referendum) as against the Constitution in Ukraine and also problematic in terms of protecting territorial integrity," the top government spokesman told reporters.
At a later press conference, Prime Minister Shinzo Abe also appealed for all parties to respect international law.
"We have been urging all parties concerned to act carefully in a self-restrained and responsible manner, scrupulously abide by relevant international laws, and respect the sovereignty and territorial integrity of Ukraine," Abe said.
Japan has found itself in limbo, between its longtime ally the United States and Russia, as a result of the Ukrainian crisis.
Abe and Russian President Vladimir Putin have built a close personal relationship, having met five times over the past year as Abe worked to improve Russo-Japanese relations.
Abe wants to resolve a territorial dispute over Russian-held islands off Hokkaido, called the Northern Territories in Japan and the Southern Kurils in Russia, which has festered for nearly 70 years and hindered improving relations between the neighboring powers even after the Cold War ended.
Abe has made improving relations a high priority for various economic and strategic reasons, a major one being Russia's potential as a major energy supplier to Japan, whose need to import fossil fuels has soared with the shutdown of all its nuclear power plants in the wake of the 2011 Fukushima Daiichi nuclear disaster.
At Monday's press conference, Abe again noted that "furthering Japan-Russia relations will benefit national interests."
Tokyo plans to send Shotaro Yachi, head of the secretariat of Japan's new National Security Council, to Russia soon to discuss the Ukraine crisis.