Japanese Prime Minister Fumio Kishida spoke Tuesday with Ukraine's president to back the country's territorial integrity in the face of a possible Russian invasion and urge a diplomatic resolution to the stand-off.

The call came as the Kremlin said it had pulled some forces back from Ukraine's borders, and President Vladimir Putin began talks in Moscow with German Chancellor Olaf Scholz.

Kishida "reiterated my consistent support for the integrity of sovereignty and territory (of Ukraine)" in the conversation with President Volodymyr Zelensky.

Japan is also ready to provide assistance to Ukraine in the form of loans of at least $100 million, Kishida told the Ukrainian leader.

The Japanese prime minister expressed "grave concern" about the situation and urged a diplomatic solution, while warning that if Russia invaded "we would respond appropriately, including sanctions, in cooperation with the G7 and the international community".

He declined to be drawn on what Zelensky had said during the call, which came as Ukraine's foreign minister said he believed a further Russian escalation had been prevented.

Kishida spoke earlier with European Commission President Ursula von der Leyen, pledging to "continue close coordination for de-escalation".

Japan's Prime Minister Fumio Kishida is expected to call Ukraine's president
Japan's Prime Minister Fumio Kishida is expected to call Ukraine's president POOL via AFP / Koji Sasahara

On Monday, a statement by finance ministers from the G7 group of most developed nations warned they were ready to impose sanctions that would "have massive and immediate consequences on the Russian economy" in the event of an invasion.

Japan's Foreign Minister Yoshimasa Hayashi on Tuesday declined to specify what form sanctions might take but said the measures would be implemented multilaterally.

Japan's defence minister also warned Tuesday of an increased Russian naval presence in the Sea of Japan and the southern part of the Sea of Okhotsk, which he suggested was intended "to show off the capability to operate in the East and West, along with the Russian military's recent movement around Ukraine".

Japan and Russia have complex relations and did not sign a peace treaty after World War II because of a lingering dispute over four islands claimed by Moscow in the closing days of the conflict.

The islands, off the northern coast of Japan's northernmost island of Hokkaido, are known as the southern Kurils in Russia and the Northern Territories in Japan.

Tokyo has shown support for its allies in Europe by offering liquified natural gas imports to help allay fears of a supply crunch if tensions around Ukraine disrupt energy supplies.

Last week, Japan announced it had diverted multiple gas shipments to Europe, with delivery expected this month and more on the way in March.

No details on the amount of gas were given, but in their call Tuesday, von der Leyen expressed "appreciation" for the move and Kishida pledged to continue cooperation to ensure energy security.