The UK and US have expressed "deep concern" that Russia has amassed tens of thousands of troops at the Ukraine border, as the allies warned of consequences if there is an invasion.
Foreign Secretary Liz Truss discussed the threat of a Russian incursion into Ukraine during talks with her US and German counterparts before a G7 foreign ministers meeting in Liverpool on Saturday.
With US Secretary of State Antony Blinken, she agreed there would be "serious consequences" for Moscow if troops were sent across the border.
According to US intelligence, Russia has stationed about 70,000 troops near its border with Ukraine and has begun planning for a possible invasion as soon as early next year.
US president Joe Biden has spoken to Prime Minister Boris Johnson and the leaders of Germany, Italy and France twice this week as they discuss how to deal with the threat.
A spokesman for the Foreign, Commonwealth and Development Office (FCDO) said "any incursion by Russia would be a strategic mistake for which there would be serious consequences,
"The Foreign Secretary and secretary Blinken both agreed on the importance of defending and promoting freedom and democracy, and the need for a unity of purpose from the G7 to achieve this."
Ms Truss spoke to the new German foreign minister Annalena Baerbock about the "need to stand up to autocratic regimes that threaten the free world", and unity in the face of Russia’s "threat" to Ukraine.
Speaking to broadcasters ahead of the meeting, Ms Truss said she was working to make sure there would be "severe economic consequences" if Moscow mobilised against Kiev.
She told allies from the US, Canada, France, Germany, Italy and Japan they needed to "defend ourselves against the growing threats from hostile actors".
Opening the main plenary as part of the UK’s year-long G7 presidency, she said: "We need to come together strongly to stand up to aggressors who are seeking to limit the bounds of freedom and democracy.
"To do this, we need to have a strongly united voice, we need to work to expand our economic and security partnerships around the world, bringing more into the sphere of countries who stand up for the values we believe in."
Ms Truss also spoke about "growing economic ties" to ensure "all nations have alternatives to dealing with authoritarian regimes", with the UK looking to convince major economic powers to wean themselves off reliance on cheap Russian gas.