Leaders from the Group of Seven industrialized nations are considering holding a virtual meeting at an early date, possibly around Feb. 24, over the crisis in Ukraine, amid mounting fears of a Russian invasion, sources close to the plan said Wednesday.

The envisioned summit, where they will affirm the group's unity over the crisis, would come after an emergency meeting of the G-7 foreign ministers. A spokesperson for the foreign ministry of G-7 host Germany reportedly said the foreign ministers will meet in Munich on Saturday.

Specific sanctions that would be imposed on Russia in the event of an incursion are also expected to be on the agenda of the foreign ministerial meeting, likely to take place in person on the sidelines of the Munich Security Conference.

The conference is a three-day multinational forum on international security policy slated to start Friday.

Foreign Minister Yoshimasa Hayashi plans to represent Japan at the meeting, also involving Britain, Canada, France, Germany, Italy, the United States, plus the European Union.

The United States and other Western allies, including Britain, have already warned of sanctions being imposed on Russia if Moscow invades neighboring Ukraine.

In a parliament session on Wednesday, Hayashi said Japan will "coordinate with the G-7" in dealing with the Ukraine crisis, including "imposing sanctions should there be a Russian invasion," while it continues to seek a solution through diplomatic dialogue.

On top of attending the foreign ministerial meeting, Hayashi is also seeking to hold separate talks with his counterparts to discuss how to defuse the current tensions, the sources said.

During phone talks on Wednesday, Prime Minister Fumio Kishida and British Prime Minister Boris Johnson agreed they would not accept any unilateral change in the status quo by force in reference to Moscow's possible military action against Ukraine.

Kishida told reporters after their talks that he and Johnson affirmed their consistent support for the sovereignty and territorial integrity of Ukraine.

The leaders also agreed to continue diplomatic efforts for de-escalation.

Kishida held separate phone talks Tuesday with Ukrainian President Volodymyr Zelenskyy and Ursula von der Leyen, president of the European Commission, the executive branch of the EU.

Earlier this week, the G-7 finance ministers warned Russia of economic sanctions that would have "massive and immediate" consequences should it commit any aggression against Ukraine.

Tensions were heightened as Russia had amassed some 150,000 troops near Ukraine, a massive military buildup that follows its annexation of Crimea in 2014. But Moscow has denied it intends to invade Ukraine.

In a move that could lead to de-escalation, Russia's military said Tuesday some troops were returning to their bases following exercises near Ukraine.

But U.S. President Joe Biden has said a partial Russian troop withdrawal has not yet been verified and that "an invasion remains distinctly possible."

Russia has been asserting that its security is under threat with the North Atlantic Treaty Organization's eastward expansion and the possibility of the former Soviet republic becoming a member of the security bloc.

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