Hungary’s nationalist prime minister, Viktor Orbán, said on Saturday that the EU was sliding toward oblivion, in a rambling anti-west speech in which he warned of a new, Asia-oriented “world order” while throwing his support behind Donald Trump’s US presidential bid.

“Europe has given up defending its own interests,” Orbán said in Băile Tuşnad, a majority ethnic Hungarian town in central Romania. “All Europe is doing today is following the US’s pro-Democrat foreign policy unconditionally … even at the cost of self-destruction.

“A change is coming that has not been seen for 500 years. What we are facing is in fact a world order change,” he added, naming China, India, Pakistan and Indonesia as becoming the “dominant centre” of the world.

Orbán alleged that the US was behind the 2022 explosions that damaged the Nord Stream gas pipelines built to carry gas from Russia to Germany, calling it “an act of terrorism carried out at the obvious direction of the Americans”. He did not offer any evidence to back up the claim.

The far-right leader’s remarks come amid growing criticism from his European partners after he embarked on rogue “peace mission” trips to Moscow and Beijing this month aimed at brokering an end to Russia’s war in Ukraine. Orbán is widely considered to have the warmest relations with the Kremlin among all EU leaders.

On Ukraine, Orbán cast doubt on the war-torn country becoming a member of Nato or the EU. “We Europeans do not have the money for it. Ukraine will revert to the position of a buffer state,” he said, adding that international security guarantees “will be enshrined in an agreement between the US and Russia”.

Throughout Russia’s war in Ukraine, Orbán has broken with other EU leaders by refusing to provide Kyiv with weapons to defend against Russian forces and has routinely delayed, watered down or blocked efforts to send financial aid to the country and impose sanctions on Moscow.

Orbán typically uses the annual Tusványos Summer University platform in Romania to indicate the ideological direction of his national government and to deride the standards of the EU bloc, which Hungary joined in 2004.

Hungary currently holds the EU’s rotating presidency, during which Orbán has vowed to “make Europe great again” and has endorsed Trump’s candidacy in this year’s US presidential election. Orbán visited Trump twice this year at the former president’s beachside compound in Mar-a-Lago.

Orbán said on Saturday that Trump’s bid for re-election aimed “to pull the American people back from a post-nationalist liberal state to a nation state” and he rehashed a slew of conservative tropes that Trump was being penalised unfairly to prevent his electoral bid.

“That is why they want to put him in prison. That’s why they want to take away his assets. And if that doesn’t work, that’s why they want to kill him,” Orbán said, referring to an assassination attempt on Trump at a Pennsylvania rally this month.

The US ambassador to Hungary, David Pressman, responded to Orbán’s comments on Saturday in a post on X, saying such rhetoric “risks changing Hungary’s relationship with America”.

“We have no other ally or partner … that similarly, overtly and tirelessly campaigns for a specific candidate in an election in the United States of America, seemingly convinced that no matter, it only helps Hungary – or at least helps him personally,” Pressman said, and he went on to accuse Orbán of peddling “Kremlin conspiracy theories about the United States. Hardly what we expect from an ally.”

Orbán’s remarks on Saturday are not the first time he has used the festival in Transylvania to stir controversy. In 2014, Orban declared for the first time his intention to build an “illiberal state” in Hungary, and in 2022 he sparked international outrage after he railed against Europe becoming a “mixed-race” society.

He doubled down on his long-held anti-immigration stance on Saturday, saying it was not an answer to his country’s ageing population.

“There can be no question of a shrinking population supplemented by migration,” he said in his Saturday address. “The western experience is that if there are more guests than owners then home is no longer home. This is a risk that should not be taken.”

The EU’s longest-serving leader, Orbán has become an icon to some conservative populists for his firm opposition to immigration and LGBTQ+ rights. He has also cracked down on the press and judiciary in Hungary and has been accused by the EU of violating rule of law and democracy standards.