Hungary's nationalist Prime Minister Viktor Orban has won a fourth term by a landslide in the country's general elections, near-complete results show.

His right-wing Fidesz party had 53.1% of votes with 98% of the count complete, preliminary results show.

The opposition alliance led by Peter Marki-Zay was far behind with 35%.

In his victory speech, Mr Orban criticised Brussels bureaucrats and Ukraine's President Volodymyr Zelensky, calling them "opponents".

"This was a huge victory," Mr Orban told jubilant supporters in the capital Budapest, late on Sunday.

"They can see it from the Moon, but certainly from Brussels as well."

Hungary shares a border with Ukraine and has taken in more than half a million refugees so far. Mr Orban insists that by helping the people, but refusing to supply weapons to Ukraine, he is keeping Hungary out of the war.

Mr Zelensky has repeatedly criticised Mr Orban's policies.

When officially confirmed by Hungary's electoral commission, the victory will be Fidesz's fourth successive win since 2010.

The National Election Office said Fidesz would have 135 seats, a two-thirds majority, and the opposition alliance would have 56 seats - again, based on preliminary results.

Mr Orban, 58, has had a fraught relationship with the EU, which considers that Fidesz has undermined Hungary's democratic institutions.

In his 12 years in power, Mr Orban has rewritten the constitution, filled the top courts with his appointees, and changed the electoral system to his advantage.

During campaigning, the opposition's catch-phrase was "Orban or Europe".

Their candidate Peter Marki-Zay argued that Hungary should join Poland, the UK and others in supplying arms to Ukraine. And if called upon, and only within a Nato framework, should even consider sending troops.

The opposition complained that Fidesz had isolated Hungary from the European mainstream, and from consensual democracy, fairness and decency.