Fresh from a landslide election win in April, Hungary's combative Viktor Orban was formally sworn in as prime minister Monday, launching a fresh attack against Brussels and a "suicidal" West.

The central European country is currently in talks with other EU members seeking to push through a Russian oil ban following Moscow's invasion of Ukraine.

Orban, who has sought close ties with Russian President Vladimir Putin in recent years, has said he would not support the proposed ban, citing his country's dependency on Russian oil. 

Urging the EU to respect the sovereignty of nation states, Orban said "cultural alienation is growing between the western half of Europe and Hungary".

"That is because we believe in the Christian civilisational foundations of Europe, and in the nation, which Brussels has given up," he told parliament after formally being reelected as premier in the 199-seat assembly by 133 votes to 27 against.

One opposition party walked out of the chamber in protest over what they see as an unlevel playing field, calling the new government "illegitimate".

European Commission President Ursula von der Leyen and European Council President Charles Michel both congratulated Orban on Twitter on Monday for his re-election.

"The EU faces unprecedented challenges. I look forward to working together to ensure we can collectively address them successfully," von der Leyen wrote.

In his wide-ranging address, Orban told newly-elected deputies that "the coming decade will be an era of dangers, uncertainty, and war".

Alongside looming economic recession, an energy crisis and the threat of pandemics Europe also has to contend with "a regenerating suicidal wave in the Western world", said the 58-year-old.

He said "gender madness" and "the great European population replacement programme" were "suicidal experiments", evoking a far-right conspiracy theory according to which white Europeans are being deliberately supplanted by non-white immigrants.

On April 3 Orban's right-wing Fidesz party won its fourth consecutive two-thirds majority since 2010, granting it further legislative carte blanche to amend the constitution and fast-track new laws.

Now transformed into what Orban calls an "illiberal state" Hungary has regularly clashed with Brussels over rule of law, migration and LGBTQ rights among many issues.

Some of Orban's opponents suspect that he wants to steer Hungary out of the EU, and criticise his close relationship with Russian President Vladimir Putin.

"It is in our interest that it remains (a member) in the next decade," Orban said on Monday.