Hungarian Prime Minister Viktor Orban's Fidesz party has won a fourth successive landslide victory.

With 94 percent of votes counted, Fidesz polled 53 percent compared to 35 percent for the opposition coalition, according to results from the national election office, meaning the party will retain its two-thirds majority in parliament.

His critics say the victory could embolden Orban in what they say is an erosion of democratic norms, media freedom and the rights of LGBTQ people.

"We have scored a victory so big, that it can be seen even from the Moon, but definitely from Brussels," Orban, who has built a career on portraying himself as a combative leader battling EU bureaucrats, told jubilant supporters as the extent of his victory became clear.

Opposition leader Peter Marki-Zay admitted defeat on Sunday evening. He told supporters: "I will not hide my sadness and my disappointment," accusing Fidesz of running a campaign of "hate and lies."

Marki-Zay said the opposition had done "everything humanly possible" but that the campaign had been "an unequal fight" given the way in which he and other anti-Fidesz politicians had been all but banished from state media.

The war in Ukraine dominated much of the campaign, with Orban and his opponents clashing over how much support to offer Kyiv.

Orban has condemned Russia's military action and has not vetoed any European Union sanctions against Moscow, even though he said he did not agree with them.

But he has banned any transport of arms to Ukraine via Hungarian territory, facing criticism from his nationalist allies in Poland, and said benefits of close ties with Russia include gas supply security.

An early morning cold snap across much of the country did not dissuade voters from casting their ballot, with initial turnout figures of 67.8 percent – just below the previous record set in 2018 of 68.1 percent.

In a nod to the cold weather, the Fidesz campaign took to Facebook, posting a photo of Orban early on Sunday holding a broom on a snowy porch with the accompanying comment "Let's sweep them away," in an apparent reference to his opponents.

At Fidesz's official election night function in Budapest, the party faithful gathered on the banks of the Danube river, where large television screens were set up.

Opposition groups align

Across town, the opposition United for Hungary group came together at Budapest's ice-skating rink to await results. The big-tent alliance consists of six diverse parties, including socialists, greens and the far-right.

Opposition strategists say teaming up had given them the best chance of unseating Orban.

Hungarians living abroad complained of long voting lines at embassies in London, Brussels and Berlin.

The election result will likely be closely watched in Brussels given the Orban government's high-profile clashes with the EU over judicial independence, media freedoms and human rights.

"Without wanting to sound overly dramatic, it's a tragedy. Looks like the end of whatever dreams one might have had of democracy in Hungary," an EU official quoted by Reuters said.

"We'd have to cut money transfers so that he doesn't build his own oligarchy with our money."

In Poland, Orban's re-election was welcome with mixed feelings among the ruling nationalists.

"Putin is a long-term threat also for Hungary and whoever doesn't see that is making a big mistake," Polish deputy foreign minister Marcin Przydacz said on Monday.