The Group of Seven industrial powers on Tuesday said they were more united than ever as they criticised China's added pressure on Taiwan and Russia's threat to station nuclear weapons in Belarus while it wages war in neighbouring Ukraine.

"The strength of the solidarity between the G7 foreign ministers is at a level not seen before," Japan's Foreign Minister Yoshimasa Hayashi said at a press conference after hosting a meeting of the group in the Japanese resort town of Karuizawa.

The show of unity comes after French President Emmanuel Macron this month said the European Union should reduce its dependency on the United States and cautioned against being drawn into a Taiwan crisis.

Beijing views Taiwan as Chinese territory and has not renounced the use of force to take the democratically governed island. Taiwan President Tsai Ing-wen says only the island's people can decide their future.

The G7 communique highlights how the dual issues of Russian military intervention and fears of similar action by China against Taiwan have been a focus of the three-day meeting.

The group, which comprises the United States, Japan, Germany, Britain, France, Italy and Canada, described Russia's threat to put nuclear weapons in Belarus as "unacceptable". It said "any use of chemical, biological or nuclear weapons in Ukraine "would be met with severe consequences."

Russian President Vladimir Putin last month said Russia would station shorter-range, so-called tactical nuclear weapons because the NATO military alliance was expanding towards Russia's borders.

It was the first time since the Cold War ended three decades ago that Russia has suggested stationing nuclear forces in another country, raising the stakes in its intensifying standoff with the West over Ukraine.

The G7 ministers also agreed that peace and security in the Taiwan Strait was critical and opposed militarisation of the South China Sea. They called on Beijing to act as a responsible member of the international community. (Reporting by Sakura Murakami and Humeyra Pamuk; Writing by Tim Kelly; Editing by David Dolan and Lincoln Feast)