Speaking to a crowd after the preliminary results were announced, Mr Orban (pictured) said his party had won an 'extraordinary victory'

Hungarian Prime Minister Viktor Orban has hailed an 'extraordinary victory' after his party was projected to win a landslide victory in elections.

With almost 98 percent of votes counted, Orban's Fidesz party has won 48.81 per cent of the vote, the National Election Office (NVI) said, surpassing even the expectations of many within Fidesz.

This is expected to translate to 134 seats in parliament.

Nationalist party Jobbik is predicted to 27 seats, the election office's website said, while the socialist party was expected to win 20 seats.

Jobbik's chairman, Gabor Vona, resigned in the wake of the result.

'Jobbik's goal, to win the elections and force a change in government, was not achieved,' Vona told a late-night news conference. 'Fidesz won. It won again.'

Speaking to a crowd in Budapest after the preliminary results were announced, Mr Orban said his party had won an 'extraordinary victory'.

He said: 'We have won. Hungary today has won a major victory - an extraordinary victory.

'It's now that we must be humble. We now have a major battle behind us - this has been a decisive win. We have created another opportunity and in the future we will be able to defend the interests of our country.

'Things are up and running and we know what path we're going to follow.'

Victorious Orban said: 'We have won. Hungary today has won a major victory - an extraordinary victory'

Hungarian Prime Minister Viktor Orban addresses the supporters after the announcement of the partial results of parliamentary election in Budapest

Hungarian Prime Minister Viktor Orban, expected to win a third consecutive term, and his wife Aniko Levai, vote at a polling station in a school in Budapest

Fidesz is seeking a third consecutive term in office and has won 49.15 per cent of votes, according the NVI, which said turnout had reached 68.80 per cent. Pictured: Crowds celebrate in Budapest

Hungarian citizens queue in the rain to cast their ballots in London as their country goes to the polls in a parliamentary election today

Opinion polls had consistently put Mr Orban and his right-wing Fidesz party 20 or more points clear of their nearest rivals, Jobbik, a far-right party which has been moving towards the centre, and the centre-left Socialists.

At end of his speech, Orban led the crowd in singing a song from the country's 1848 revolution, 'Long Live Hungarian Freedom'.

One supporter, 53-year-old Eva Halasz, said: 'Viktor is the only leader for Hungary, this proves he has the nation behind him, there is no-one in this country like him, there is no opposition here.'

France's far-right leader Marine Le Pen tweeted her congratulations on Sunday night, saying the 'reversal of values and mass immigration promoted by the EU has been rejected once again'.

Dutch far-right leader Geert Wilders was also quick to welcome the 'excellent result'.

'These elections have proved that migration is indeed a winning card for Orban's Fidesz. In the current Hungarian context, migration prevails against all other issues, from corruption to healthcare,' analyst Andras Biro-Nagy from the Policy Solutions think-tank told AFP.

In terms of what a third Fidesz term may hold, Biro-Nagy said 'we should take seriously what Orban promised to his opponents [in a speech] on 15 March'.

In that speech, Orban had said he would take unspecified 'moral, political and legal' measures against his opponents after the vote, prompting fears of a crackdown on opposition.

Nationalist leader Mr Orban claims the opposition, collaborating with the United Nations, the European Union and philanthropist George Soros, wants to turn Hungary into an 'immigrant country,' threatening its security and Christian identity.

Orban will likely seize on the results as vindication of his clashes with EU institutions over his hardline anti-immigration policies and rejection of the EU's refugee resettlement programme, as well as his moves to clamp down on civil society groups.

An Orban victory will also provide a fillip for other nationalist politicians and those on the far-right who look to him as an inspiration.

All 199 seats in the Hungarian parliament were up for grabs, with the opposition keen to make sure Mr Orban's bloc does not win a super-majority which would allow the leader to push through further constitutional changes.

Previous constitutional changes have put Mr Orban on a collision course with Brussels, including moves to erode the independence of the media and the judiciary, as well as a crackdown on civil society groups, particularly those funded by Hungarian-born US billionaire George Soros.

The government has been accused by critics of using anti-Semitic stereotypes in its relentless campaign against Mr Soros, who is Jewish.

Jobbik party leader Gabor Vona, main opponent to current Prime Minister Viktor Orban, and his wife Krisztina Vona-Szabo, arrive at a polling station in Gyongyos

Gergely Karacsony, right, the leading left-wing candidate for prime minister, casts his vote accompanied with his family at a polling station in Budapest

Gabor Vona of the Jobbik party said the question was not about migration but about the large number of Hungarians who were leaving the country and heading to Western Europe in search of higher wages and better prospects.

'Today will decide whether Hungary becomes an emigrant country or not - and I wouldn't like Hungary to be an emigrant country,' Mr Vona said.

Mr Orban has campaigned heavily on his unyielding anti-migration policies, though voters claim they are more concerned with poverty, government corruption and the country's underfunded health care system.

The PM's anti-migrant rhetoric resulted in February in a spat with the UN's top human rights official, who in February accused Mr Orban of xenophobia and racism.

The PM and his wife Aniko Levai were pictured voting at a school in Budapest this morning, while Hungarian citizens in London were seen queuing in the rain to cast their ballots.

Opposition leaders said they were encouraged by high early turnout.

First Lady Anita Herczegh and her husband, Hungarian President Janos Ader, who belongs to the same party as Orban, cast their ballots at a polling station in Budapest this morning

A voter approaches ballot boxes at a polling station in Budapest. Officials said the turnout at 11am local time was the highest since at least 1998

Supporters of the pro-European Union movement Pulse of Europe wave EU flags as they gather in front of the Brandenburg Gate to express their support for pro-European elements in Hungary

Orban, pictured in a car outside the polling station, could use a super-majority in the Hungarian parliament to push through further constitutional changes

Hungarian citizens were pictured waiting in long queues in the rain to cast their ballots in London, as their country went to the polls in a parliamentary election today

According to the National Election Office, 2.35 million voters had cast ballots by 11am local time, or 29.93 percent of those eligible. That was the highest turnout figure at that time since at least 1998.

'We are celebrating democracy and it seems like this feast will be beautiful because many of us are taking part,' said Gergely Karacsony, the leading candidate of the left-wing Socialist and Dialogue parties.

Jobbik's Mr Vona urged his supporters not to become complacent.

'Figures show that it will be an election with a high voter turnout. But this is not the time to sit back,' Mr Vona said after voting his home city of Gyonygyos in northern Hungary. 'This is when all those who want a change of government ... ask all those who have yet to vote to by all means go and vote.'

Uncertainties about Mr Orban's margin of victory are caused by Hungary's electoral system in which voters cast two ballots, one for an individual candidate in their region and another for a party list.

Opposition parties have urged Hungarians to vote tactically for the opposition candidate with the best chance to defeat the Fidesz candidate in the 106 individual districts. Another 93 seats will be distributed based on votes for entire party lists.

Some 8.3 million Hungarians are eligible to vote, with preliminary results expected on Sunday night.

Poland's rightwing Prime Minister Mateusz Morawiecki was quick to congratulate his Hungarian counterpart Viktor Orban, Warsaw's closest ally in the EU, on winning a third straight term in a crushing electoral victory.

"The road to reform is never easy," Morawiecki tweeted, adding that "the support of the majority of society shows that it's worthwhile to make the effort."

"I wish you success, for Hungary and for Europe," said Morawiecki, leader of the Law and Justice (PiS) government which has cultivated close ties with Orban.

Poland and Hungary are allies in battles with EU institutions over their anti-migrant stance and drive for a more decentralised EU with greater powers for member states.

On a visit to Budapest Friday, Jaroslaw Kaczynski, leader of Poland's governing PiS party, also gave Orban his endorsement.

In his victory speech on Sunday night, Orban himself thanked Kaczynski for his support.

Poland's government has had its own run-ins with Brussels over its changes to the judicial system.

Orban's nationalist Fidesz party won around 49 percent of the vote, an improvement on its score from four years ago. The result may even gift Fidesz a two-thirds majority in parliament, which would enable it to change the constitution.