The G7 foreign ministers on Monday called on Russia to stop its "provocations" and "de-escalate tensions" following its troop build-up on the border with Ukraine.
The ministers from the Group of Seven leading industrialised countries "are deeply concerned by the large ongoing build-up of Russian military forces on Ukraine's borders and in illegally-annexed Crimea," they said in a statement.
"These large-scale troop movements, without prior notification, represent threatening and destabilising activities," the statement added.
"We call on Russia to cease its provocations and to immediately de-escalate tensions in line with its international obligations."
The G7 — the United States, Britain, France, Germany, Italy, Japan and Canada — also urged Russia to uphold international "principles and commitments that it has signed up to on transparency of military movements".
The ministers met amid a surge in diplomatic activity prompted by concerns that the years-long conflict in eastern Ukraine could escalate sharply as clashes with pro-Russian separatists have surged.
"We reaffirm our unwavering support for the independence, sovereignty and territorial integrity of Ukraine within its internationally recognised borders," the G7 said. "We support Ukraine's posture of restraint."
Ukraine has accused Russia of amassing thousands of military personnel on its northern and eastern borders as well as on the annexed Crimean peninsula.
The Kremlin has not denied the troop movements but insisted that Moscow does not intend to threaten anyone.
The White House this week said the number of Russian troops at the border with Ukraine was now greater than at any time since 2014, when the conflict erupted after Russia's annexation of Crimea from Ukraine.
Fighting subsided in 2020 as a ceasefire agreement took hold last July, but clashes have picked up again since the start of the year, with each side blaming the other.
On Thursday Ukraine's President Volodymyr Zelensky visited the eastern frontline, speaking with soldiers in the trenches.
Since 2014, the conflict in Ukraine's east has claimed more than 13,000 lives and displaced many others, while negotiations for a lasting peace deal have stalled.