Voting is under way in Hungary, with opinion polls pointing to a third consecutive term for Prime Minister Viktor Orban.

Mr Orban and his right-wing Fidesz party are 20 points or more ahead of the far-right Jobbik party and the centre-left Socialists.

Polling stations opened at 06:00 local time (04:00 GMT) on Sunday and will close at 19:00.

Preliminary results are expected one or two hours after voting ends.

While Fidesz is expected to win a parliamentary majority, analysts are eyeing the turnout and whether Mr Orban's party loses its "supermajority".

This is the two-thirds control of the 199-seat legislature that has allowed Fidesz to pass controversial laws putting pressure on the judiciary and the press.

What are Viktor Orban's policies?

Mr Orban refused to publicly debate with his opponents during the campaign or speak to the independent media, speaking instead at rallies for his supporters.

These addresses focused on one core policy - stopping immigration.

"Migration is like rust that slowly but surely would consume Hungary," Mr Orban said at his final rally on Friday.

Under Mr Orban, Hungary built a fence along its borders with Serbia and Croatia in 2015 to stop illegal migrants.

His anti-immigration measures and tough rhetoric have seen him clash with the European Union in the past.

Mr Orban is an avowed Eurosceptic who opposes further EU integration. He refused to take part in the EU's refugee resettlement programme, and he has praised Russian leader Vladimir Putin.

If he wins, as is likely, Mr Orban has promised to cut income tax and pass pro-growth economic policies.

His administration has presided over strong economic growth, which he says would be threatened under the opposition.

Who are the opposition parties?

A poll on Friday put Fidesz on 46% among decided voters, more than 20 points ahead of their nearest rivals Jobbik, on 19%.

Formerly a far-right group who agitated against Hungary's Roma community, Jobbik has tried to claim the centre ground in recent years.

Rebranding itself as a moderate "conservative people's party", its leader Gabor Vona has called for a change in government and railed against Mr Orban.

"Viktor Orban is a burnt-out politician, interested only in corruption and football," he once said.

The centre-left Socialists meanwhile were on 14% in Friday's poll and not thought to pose a threat to Fidesz.

However, one-third of voters remain undecided, and an upset is not being ruled out.

In February, the southern town of Hodmezovasarhely elected a mayor backed by all the main opposition parties. It had been considered a Fidesz stronghold.

Analysts believe a high turnout could benefit the opposition, and tactical voting could in theory strip Fidesz of its 133-seat domination of Hungary's parliament.

However, given his commanding lead in the polls, an outright defeat for Mr Orban is unlikely.