Tokyo has told Washington it opposes a suggestion by U.S. President Donald Trump to add Seoul to the Group of Seven summit, diplomatic sources said, in a move likely to further chill already frozen ties with South Korea.

The message, in which Tokyo claimed Seoul is out of lockstep with G7 members on Chinese and North Korean issues, was conveyed by a high-level Japanese government official immediately after Trump on May 30 broached the idea of inviting Australia, India, Russia and South Korea to this year's summit. The U.S. leader is due to preside over the summit later this year.

The diplomatic sources said the Japanese official was told by the U.S. side that any final decision on the issue would rest with Trump.