Volodymyr Zelensky confronted Viktor Orban for a “frank” conversation on Sunday amid a row over EU membership for Ukraine and more funding for its war effort.

The meeting on the sidelines of the inauguration of Javier Milei, Argentina’s newly-elected president, came just days before a European Union summit set to decide on membership talks for Kyiv and additional military aid.

Footage showed the Ukrainian and Hungarian leaders having an animated conversation in the Argentine parliament in Buenos Aires.

“It was as frank as possible and obviously it was about our European affairs,” Mr Zelensky said on Sunday in his nightly video address.

Bertalan Havasi, Mr Orban’s press chief, confirmed the apparently spontaneous meeting but did not say if Mr Zelensky had succeeded in changing the Hungarian prime minister’s position.

“With regards to Ukraine’s EU accession, Viktor Orban signalled that the member states of the European Union were continuously discussing the issue,” said Mr Havasi.

Accession talks can only begin if every EU member state supports them.

Mr Orban, who boasts about his ties with Vladimir Putin, the Russian president, has repeatedly said he opposes Ukraine joining the bloc.

He has also threatened to veto moves to provide Kyiv with an additional £42 billion in financial aid between now and 2027.

Securing new financial assistance from Europe is critical as doubts mount over future US support for Kyiv, which relies heavily on Western financial aid.

“Ukraine is known to be one of the most corrupt countries in the world,” he told French newspaper Le Point on Friday. “It’s a joke!”

“We cannot take the decision to start a process of accession negotiations,” Mr Orban added.

The Hungarian prime minister has insisted that Ukraine is not ready to join the EU and that this week’s summit on Thursday and Friday should not even discuss the possibility of the war-torn nation becoming a member.

He has instead called for a “strategic discussion” to be held on the long-term sustainability of EU support for Ukraine’s defence against Russia.

Emmanuel Macron has invited Mr Orban to dinner in Paris on Thursday in a bid to convince him to support Ukraine.

But Mr Orban told Le Point that “my idea is to try to convince him to listen to my arguments.”

Mr Zelensky was a star guest of Mr Milei at his inauguration over the weekend and was given a menorah as a gift in tribute to his Jewish ancestry.

He was due to arrive in Washington on Monday for talks with Joe Biden, the US president, and Mike Johnson, the speaker of the House of Representatives, about the ongoing Russian war in Ukraine and the “vital importance” of continued US aid to Kyiv.