By Kirsty Needham

SYDNEY (Reuters) - U.S. security ally Australia, which has provided A$1.5 billion in support to Ukraine in its war with Russia, said on Thursday that Moscow was the aggressor in the conflict and it must be resolved on Kyiv's terms.

U.S. President Donald Trump denounced Ukrainian President Volodymyr Zelenskiy as a "dictator" on Wednesday and warned Zelenskiy had to move quickly to secure peace or risk losing his country.

The extraordinary attacks - a day after Trump claimed Ukraine was to blame for Russia's 2022 invasion - heightened concerns among U.S. allies in Europe that Trump's approach to ending the Russia-Ukraine conflict could benefit Moscow.

Australia's Defence Minister Richard Marles said the conflict had seen extraordinary loss of life but it cannot be peace on any terms.

“The war in Ukraine must be resolved on Ukraine's terms, because the aggressor here is Russia, and what we see at stake is the integrity of the rules‑based order, the global rules-based order,” Marles told reporters on Thursday.

“We welcome attempts to bring it to an end, but it cannot be on any terms, it must be on Ukraine’s terms, and we'll continue to support Ukraine in that.”

Australia is a major security ally for the United States in the Indo Pacific, where both countries have expressed concern over China's military build up.

Australia's conservative opposition also criticised Trump's position on Ukraine.

"I think President Trump has got it wrong," Peter Dutton, the leader of the Liberal opposition party, said on Thursday.

"The thought that President Zelenskiy or the Ukrainian people started this battle or somehow they were responsible for the war is just wrong," said Dutton, who was defence minister when the Ukraine conflict started.

"Australia should stand strong and proud with the people of Ukraine. It's a democracy, and this is a fight for civilisation. Vladimir Putin is a murderous dictator, and we shouldn’t be giving him an inch," he said.

(Reporting by Kirsty Needham)