Prime Minister Shinzo Abe will not attend an official ceremony in Moscow on May 9 to mark the 70th anniversary of the end of World War II because of a scheduling conflict, Chief Cabinet Secretary Yoshihide Suga said Tuesday.

He told a news conference that Japan's ambassador to Russia will attend the ceremony instead.

Japan has invited Russian President Vladimir Putin to visit but it was called off last year because of the Ukraine crisis.

Suga also said the rescheduling of Putin's visit has not been decided.

Abe, eyeing Russia's energy resources, had made improving ties a priority. But they have been strained by sanctions imposed by Tokyo on Moscow over the Ukraine crisis, as Tokyo seeks to stay in step with its close ally the United States.

A feud over Russian-controlled islands off Hokkaido, seized by the former Soviet Union at the end of the war, remains unresolved, precluding a formal peace treaty.

German Chancellor Angela Merkel has already declined an invitation to the ceremony due to tensions over Ukraine, though she will lay a wreath at the Monument of the Unknown Soldier in the Russian capital one day later.

The European Union and the United States accuse Russia of arming the separatists in eastern Ukraine and of reinforcing their ranks with troops. Moscow has repeatedly denied involvement and blames the United States for pushing the pro-Western government in Kiev to war.

Chinese President Xi Jinping is expected to attend the Moscow ceremony, though Beijing has yet to confirm it.

Chinese state media said Tuesday that 110 People's Liberation Army troops have already arrived in Moscow to prepare for the parade.

China and Russia have close diplomatic and trade ties.