Hungarian PM Viktor Orban and his wife Aniko Levai cast their vote at a polling station in Budapest on October 2. Photograph: (AFP)
Hungary's PM Viktor Orban has urged the electorate to spurn the EU deal, which wants to share migrants around the 28 member states through mandatory quotas
Hungarians on Sunday began voting on the EU's troubled refugee quota plan, in a referendum aimed at boosting Prime Minister Viktor Orban's self-styled campaign to defend Europe against the "threat of mass migration".
While there is little doubt his 'No' camp will comfortably win, the poll could still end in embarrassment for Orban if it fails to reach the required 50-per cent turnout and is deemed invalid.
Polling stations opened at 0400 GMT and will close at 1700 GMT, with results expected later in the evening.
"We are proud that we are the first to be able to vote on this question, unfortunately the only ones," Orban said after casting his ballot in the capital Budapest.
The firebrand leader has emerged as the populist standard-bearer of those opposed to German Chancellor Angela Merkel's "open-door" policy, in the wake of the bloc's worst migration crisis since 1945.
He has led a fierce media offensive urging the eight-million-strong electorate to spurn the EU deal, which wants to share migrants around the 28 member states via mandatory quotas without the consent of national parliaments.
Orban warned on Saturday that mass migration was a "threat... to Europe's safe way of life" and that Hungarians had "a duty" to fight the failed "liberal methods" of the "Brussels elite".
The proposal -- spearheaded by Germany and approved by most EU governments last year after antagonistic debates -- seeks to ease pressure on frontline countries Italy and Greece, where most migrants enter the EU.
But implementation has been slow. Eastern and central European nations are vehemently opposed to the plan aimed at relocating 160,000 people, many having fled war in Syria.
Hungary has not accepted a single refugee of the 1,300 allocated under the scheme and instead joined Slovakia in filing a legal challenge against it.
The referendum has incensed Western leaders and threatens to further split the quarrelling bloc, already weakened by Britain's decision in June to leave the union -- a decision Orban has blamed on the EU's handling of the migrant crisis.
European Parliament president Martin Schulz warned on Sunday that Hungary "played a dangerous game".
To cement his power at home, Orban "plays with the EU's founding principle: he questions Europe's legal basis -- which Hungary was involved in creating," Schulz told German media.
Test for election
The referendum asks voters: "Do you want the EU to be able to mandate the obligatory resettlement of non-Hungarian citizens into Hungary even without the approval of the National Assembly?"
Critics slammed the government for asking a leading question and whipping up xenophobia despite the lack of asylum-seekers in the country.
Many said they would abstain out of protest.
"I will not be a pawn in Orban's game... The question is phrased in such a way that it practically only invites one answer," said a 40-year-old farmer who accompanied his mother to a polling station in Budapest.
"It's true that the campaign was exaggerated but no-one can tell me if these migrants really are refugees of war," Zoltan, a 38-year-old lawyer and 'No' voter, told AFP.
Polls show the vote may not reach the required 50-percent threshold -- a scenario Orban has already downplayed, insisting the turnout had "no political significance".
"If there are more 'No' than 'Yes' votes, that means that Hungarians do not accept the rule that the EU bureaucrats want to impose on us," he said Friday.
Analysts say the referendum provides a testing ground for the scheduled 2018 general election, in which immigration will be a key issue.
More than 400,000 refugees, mainly fleeing war in Syria, trekked through Hungary towards northern Europe in 2015 before Hungary sealed off the southern borders with razor wire in the autumn and brought in tough anti-migrant laws, reducing the flow to a trickle.
Other countries on the so-called Balkan migrant trail followed suit, shutting the route and leading to some 60,000 migrants being now stranded in Greece.
The EU said last week it hoped to relocate half of them by the end of 2017.
A deal struck in March with Ankara to halt the influx looks shaky in the wake of a coup attempt in July.