Hungary's controversially right-wing prime minister, Viktor Orban, claimed that Poles and Hungarians have a common goal in maintaining Christianity in their countries ahead of yesterday's election from which he is expected to win a third consecutive term in power.

Orban, who declared in February that 'Christianity is Europe's last hope', claimed on Friday that Hungary's future would be decided for decades by the vote, as the nationalist leader vowed to protect his nation from the 'rust' of Muslim migrants.

'We will win again on Sunday as we have won battles in the past which looked impossible for many,' Orban told supporters waving the national flag in the town of Szekesfehervar, west of Budapest.

'We have built the fence, defended the southern border ... Migration is like rust that slowly but surely would consume Hungary.'

Earlier on Friday, Orban claimed common cause with Poland, whose governing Law and Justice (PiS) party has been criticised by the EU over its refusal to take in migrants under a quota system and over their efforts to tighten state control of their courts and media.

'We believe Poles and Hungarians have a common path, common fight and common goal: to build and defend our homeland in the form that we want...Christian and with national values,' Orban said at the unveiling of a statue marking a 2010 plane crash in Russia that killed the Polish president.

That president's twin brother, now Poland's PiS leader, Jaroslaw Kaczynski, endorsed Orban while attending the ceremony commemorating the plane crash.

In February, Orban declared that 'Christianity is Europe's last hope' after accusing politicians in Brussels, Berlin and Paris of ushering in the 'decline of Christian culture and the advance of Islam'.

During his annual state of the nation speech, Viktor Orban called for a global alliance against migration as his populist Fidesz party began campaigning for yesterday's election.

Orban said his government will oppose efforts by the United Nations or the European Union to 'increase migration' around the world.

And he claimed that Islam would soon 'knock on Central Europe's door' from both the west and the south.

In a populist rallying cry, Orban insisted that Western Europe is being overtaken by Muslims, before claiming that 'born Germans are being forced back from most large German cities, as migrants always occupy big cities first'.

The politician, who has been prime minister since 2010, is popular in Hungary but is increasingly at odds with mainstream European Union politicians and appears to thrive on controversy, including repeated clashes with Brussels.

Orban said in his speech at the Royal Castle in Budapest: 'Christianity is Europe's last hope. Our worst nightmares can come true. The West falls as it fails to see Europe being overrun.'

Domestically, Orban is popular partly because he is widely credited with reversing an economic slump in Hungary and controlling its public finances.

But internationally the 55-year-old is known to pick fights with EU partners, especially in the West.

In his controversial speech, Orban said that Europe faces a divide between nations of the East and the West, which he called an 'immigrant zone, a mixed population world that heads in a direction different from ours'.

And he went on to claim that the West wants eastern Europe to follow its lead, which could trigger an increasingly vicious struggle.

'Absurd as it may sound the danger we face comes from the West, from politicians in Brussels, Berlin and Paris,' Orban said to loud applause. 'Of course we will fight, and use ever stronger legal tools. The first is our "Stop Soros" law.'

This was a reference to the Hungarian-born US financier George Soros, whose philanthropy is seen as aimed at backing liberal and open-border values.

The right-wing Hungarian leader, who has been accused of being racist, advocated 'ethnic homogeneity' and compared Soros, a Jew, to a puppet master unleashing immigration onto Europe to undermine its cultural and economic integrity.

In turn, Soros has compared Orban to both the Nazis and the Communists, saying his rule evoked images from the 1930's, when Hungary was allied with Nazi Germany.

During the international migrant crisis, Orban ordered a double razor wire fence to be built to keep people out of Hungary.

Orban also accused the Hungarian opposition of being on the wrong side of history when it opposed his toughness on migrants.

Orban said: 'Soros has antagonised not only us but also England, President Trump and Israel too. Everywhere he wants to get migration accepted. It won't work. We are not alone and we will fight together and we will succeed.'

He cited Slovakia, the Czech Republic and Poland as allies.