European ministers called on Russia to promptly advance peace talks on Ukraine, renewing their support for an "unconditional" 30-day cease-fire.

"So far, Russia has not shown any serious intent to make progress. It must do so without delay," the ministers from six nations plus the EU said in a statement after meeting in London.

The Kremlin on Monday rejected threats of new EU sanctions if Russia refuses to agree to a cease-fire in Ukraine, calling such warnings "unacceptable ultimatums," according to Russian presidential spokesperson Dmitry Peskov.

"The language of ultimatums is unacceptable for Russia, it is not suitable. You cannot speak to Russia in such a language," Peskov told reporters in Moscow, cited by state-run news agency TASS.

He noted that similar threats had been voiced on May 10 when French President Emmanuel Macron, German Chancellor Friedrich Merz, and the British and Polish prime ministers, Keir Starmer and Donald Tusk, visited Kyiv and backed a 30-day truce proposal starting May 12.

Earlier on Monday, the German government warned that the EU would begin drafting additional sanctions against Russia if it rejects the proposed cease-fire agreement backed by European leaders and Ukraine.

The proposed truce follows a failed 72-hour unilateral cease-fire declared by Moscow from May 8 to May 11 to mark the 80th anniversary of Victory Day.