LONDON, May 19, 2025 (BSS/AFP) - The leaders of Britain, France, Germany and Italy again pressed the need for sanctions against Russia in a call with US President Donald Trump before his telephone summit with Russia's President Vladimir Putin, the British prime minister's office said.

Trump is to speak with Putin on Monday as part of his long-running effort to end the war set off by Russia's 2022 invasion of Ukraine.

"The leaders discussed the situation in Ukraine, and the catastrophic cost of the war to both sides," said a spokesman for British Prime Minister Keir Starmer in a statement on the call late Sunday.

"Looking ahead to President Trump's call with President Putin tomorrow, the leaders discussed the need for an unconditional ceasefire and for President Putin to take peace talks seriously," the spokesman added.

"They also discussed the use of sanctions if Russia failed to engage seriously in a ceasefire and peace talks."

European leaders stepped up warnings of new sanctions against Russia before negotiations between Ukrainian and Russian officials in Istanbul last Friday that ended without a breakthrough.

European governments have repeatedly accused Putin of deliberately ignoring ceasefire calls.

"The Europeans and Americans are determined to work together, in a targeted way, so that this terrible war ends quickly," German Chancellor Friedrich Merz said Sunday at the Vatican where he attended the inauguration of Pope Leo XIV.

"We have made some small steps forward in recent days ... the parties to the conflict are talking to each other," he added.

Starmer, Merz, France's President Emmanuel Macron and Poland's Prime Minister Donald Tusk also spoke with Trump after the Istanbul talks.

Amid a new burst of diplomacy, Ukraine's President Volodymyr Zelensky spoke with US Vice President JD Vance on the sidelines of the Vatican ceremony.