A low turnout in Hungary is expected to make the result of a vote against European Union migrant quotas invalid, exit polls suggest.

Some 95% of voters rejected the EU quotas, polling company Nezopont found.

However, overall turnout is expected to be around 45%, according to polls and ruling party lawmaker Gergely Gulyas - making it lower than the 50% required.

The voting paper consisted of one question: "Do you want the European Union to be entitled to proscribe the mandatory settlement of non-Hungarian citizens in Hungary without the consent of the National Assembly (Parliament)?"

Rather than trying to win, the opposition urged their supporters to stay at home and reduce the turnout figures.

Over the past year, Hungary has seen its southern border sealed with a razor wire fence and thousands of army and police border controls.

In that time it has recorded around 18,000 illegal border crossings as the numbers of migrants fleeing war and poverty has swelled.

In a letter published in a newspaper on Saturday, Prime Minister Victor Orban urged Hungarians to send a message to the EU that its migration policies were flawed and posed a threat to Europe's security.

"We can send the message that it is only up to us, European citizens, whether we can jointly force the Union to come to its senses or let it destroy itself," he wrote.