Donald Tusk is a politician who was President of the European Council, the EU’s political arm. Since leaving his role in the 27-nation bloc just over two years ago, the former Polish Prime Minister has remained at the forefront of European politics. The President of the European People’s Party has hit out at Russian President Vladimir Putin’s “aggressive” invasion of Ukraine over the last month.

Mr Tusk confirmed on Tuesday that, due to the Ukraine conflict, Poland, Slovakia and the Czech Republic have refused to participate in a meeting with Hungary in Budapest.

He said the snub of Hungary by its fellow so-called Visegrád nations was a “protest” against the “pro-Putin” policies of Hungarian Prime Minister Viktor Orbán, who is seen as an ally of the Kremlin strongman.

Mr Tusk has previously hit out at Russia over Brexit, alleging Moscow meddled in the 2016 Brexit referendum.

The public vote saw Britons decisively choose to split from the European trading bloc, which the UK joined in 1973 when it was still the European Economic Community.

However, in a 2018 speech Mr Tusk said there were “very clear” signs Russia had influenced the UK’s decision to take back its sovereignty.

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He said there were “very clear traces of Russia’s engagement in the Brexit referendum campaign”.

The ex-EU man did not provide evidence for the claims as he addressed a conference, hosted by the Pontifical University of John Paul II in Kraków in southern Poland.

The politician used the event, which explored the future of the EU, to flag Moscow’s alleged attempts to steer politics across Europe.

He continued: “Our problem is Russia, which is undermining whatever it can undermine in Europe.

“I can provide numerous examples to prove that Russians will not refrain from any means to weaken European unity.”

Another, he said, was the cyberattack on the Organisation for the Prevention of Chemical Weapons.

Despite Mr Tusk’s bold claims, he denied having an “anti-Russian obsession”.

However, he added: “If there is [a nation] somewhere whose main political priority is to disintegrate Europe, this certainly is Russia.”

During the wide-ranging speech, the politician also warned his fellow EU leaders not to “fool” themselves over the bloc’s ties with the US.

Hitting out at then-US President Donald Trump, he said: “Never before in my life has America been a problem for Europe.

“What happened under the administration of my namesake Donald Trump is a new phenomenon.

“America is sailing away from Europe today and it is intentional.”