European leaders have issued a joint statement setting out support for Ukraine and Donald Trump's efforts to end the fighting - but a Russian spy chief has warned world security faces its "most fragile moment" since 1945.

Moscow’s rejection of an immediate ceasefire in Ukraine appears to have put a summit between Donald Trump and Vladimir Putin in jeopardy, diplomats said on Tuesday, after a preparatory meeting between the top US and Russian diplomats was postponed.

Ukraine's president and European leaders are accusing Russian President Vladimir Putin of stalling on peace efforts in Ukraine.

Ukrainian President Volodymyr Zelensky is expected to push Trump for additional long-range weapons capable of striking targets inside Russian territory when he meets with Trump in Washington at the White House on Friday.

Trump, who recently spoke with Putin and met Zelenskiy, plans a summit with the Russian leader in Budapest within two weeks to push for an end to the war.

President Donald Trump says Indian Prime Minister Narendra Modi has personally assured him that India will stop buying Russian oil

Russian forces are still edging forward along several parts of the long front line in Ukraine – despite yet another call from US President Donald Trump for a combat freeze along existing lines.

Russia launched a large armoured assault on Thursday with more than 20 armoured vehicles near the eastern Ukrainian town of Dobropillia, Ukraine's Azov brigade said, adding that its forces had repelled the attack.