Hungarian Prime Minister Viktor Orban met with Donald Trump and the pair discussed the "possibilities of peace", a spokesperson for the prime minister said as he pushes for a ceasefire in Ukraine.

Trump and Orban met at Trump's Mar-a-Lago home in Florida "as the next stop of his peace mission," Orban's spokesperson said. "The discussion was about the possibilities of peace".

Nationalist leader Orban, a long-time Trump supporter, made surprise visits to Kyiv, Moscow and Beijing in the past two weeks on a self-styled "peace mission", angering NATO allies.

His meeting in Moscow with Russian President Vladimir Putin in particular vexed some other NATO members, who said the trip handed legitimacy to Putin when the West wants to isolate him over his war in Ukraine.

Orban traveled to Kyiv before visiting Moscow but did not tell Ukrainian President Volodymyr Zelenskiy about his mission to Russia, Zelenskiy said, dismissing Orban's ambition of playing the peacemaker.

"Not all the leaders can make negotiations. You need to have some power for this," Zelenskiy said earlier at a news conference at the NATO summit.

White House National Security Adviser Jake Sullivan, when asked about Orban's initiative, said Ukraine would be rightly concerned about any attempt to negotiate a peace deal without involving Kyiv.

"Whatever adventurism is being undertaken without Ukraine's consent or support is not something that's consistent with our policy, the foreign policy of the United States," Sullivan said.

Orban's self-styled peace mission has also irked many members of the European Union, whose rotating presidency Hungary took over at the start of this month.

The Hungarian embassy in Washington declined to comment on the planned meeting with Trump, which was first reported by Bloomberg.

Orban has been attending a NATO summit hosted by Democratic President Joe Biden. Hungary's delegation voiced opposition to key NATO positions, while not blocking the alliance from taking action.

Foreign Minister Peter Szijjarto told Reuters on Wednesday that Hungary believes a second Trump presidency would boost hopes for peace in Ukraine.

Orban hoped to bring an end to the war through peace talks involving both Russia and Ukraine, according to Szijjarto.

Trump has said he would quickly end the war. He has not offered a detailed plan to achieve that, but Reuters reported last month that advisers to the former president had presented him with a plan to end the war in part by making future aid to Kyiv conditional on Ukraine joining peace talks.

In the past several months, foreign officials have regularly sought meetings with Trump and his key advisers to discuss his foreign policy should he beat Biden in the Nov. 5 election. Polls show Trump widening his lead over Biden.

One adviser, Keith Kellogg, has met with several high-ranking foreign officials on the sidelines of the NATO summit, Reuters reported this week.