Japan joined the other members of the Group of Seven advanced nations on Tuesday in agreeing that Russia was probably behind a nerve agent attack in Britain last month, after having refused for weeks to assign blame.

In a statement released on Tuesday Japan time, the G-7 foreign ministers endorsed Britain's finding that "there is no plausible alternative explanation" other than Russia's responsibility for the attack on former Russian spy Sergei Skripal and his daughter, Yulia, in Salisbury on March 4.

Since the attack, the Japanese government has not joined the rest of the G-7 but merely condemned the use of chemical weapons without pointing the finger at Russia, with which it is trying to make progress on a decades-long territorial row.