Hungary -- the friendliest EU country to Russia -- has repeatedly held up initiatives to aid Ukraine or punish Russia since Moscow's invasion of its neighbour in 2022.

Anger has been rising with Budapest over the past year as it has prevented payouts from a central EU fund to reimburse member states for weapons sent to Ukraine.

Now EU officials say a fresh blockage from Hungary threatens to hold up another five billion euros ($5.4 billion) that could go towards aiding Kyiv's outgunned forces even though it was already signed off by EU leaders.

The Hungarian hold-up also threatens to delay the spending of billions more in profits from frozen Russian central bank assets that the EU expects to start receiving in July.

"We cannot let European military support to Ukraine be taken hostage of (by) other decisions which have nothing to do with this specific issue," EU foreign affairs chief Josep Borrell said after a meeting of foreign ministers in Brussels.

"Especially given the urgency of the situation -- Ukraine needs the arms now," he said.

Germany's foreign minister, Annalena Baerbock, called on Budapest "to finally allow aid to Ukraine once again, because Europe is only strong if it is united".

"We cannot accept that a single country, which also signed up to this amount a few months ago at the heads of state's council meeting, is now blocking this crucial aid for Ukraine," said Belgian Foreign Minister Hadja Lahbib.

Hungarian Foreign Minister Peter Szijjarto wrote on social media that he had faced "enormous pressure" from his EU colleagues.

He said that releasing funds now worth some 6.5 billion euros to help arm Ukraine was "unacceptable" to Budapest.

Hungary under right-wing Prime Minister Viktor Orban has long played a spoiler role inside the EU as it uses its veto for leverage in disputes with Brussels.

But Lithuania's foreign minister Gabrielius Landsbergis said that Budapest's opposition now appears to have become a "systematic approach".

"So basically, almost all of the discussions and needed solutions and decisions by EU are being blocked by just one country," he said.

"I think it has gone very, very far."