The EU referendum is expected to go down to the wire, with four polls on the eve of the ballot (22 June) showing the Leave and Remain sides are too close to call (EU referendum live blog: follow here).

Two polls put the Leave campaign ahead, while two different polls put the Remain campaign ahead, with an average of one in 10 voters still reportedly undecided.

ComRes shows the Remain side ahead by one point, with 46% saying they would vote Leave, while 45% saying they would vote Remain. Some 9% of those included said they did not know which way they would vote on Thursday (23 June).

The pollster's director, Tom Mludzinski, said: "We had seen Remain holding a comfortable lead but after the debates and the agenda switching to immigration it has narrowed the gap with Leave now in touching distance."

Meanwhile, TNS have put Leave at 43% and Remain at 41%, although it said that voter turnout will be key in deciding the outcome of the referendum. It pointed out that the 18-34 age group is strongly in favour of Remain but fewer of them will vote in comparison to older people, who lean towards leaving the EU.

Luke Taylor, Head of Social and Political Attitudes at the company, said that the figures show that: "Leave is in a stronger position than Remain but it should be noted that in the Scottish Independence Referendum and the 1995 Quebec Independence Referendum, there was a late swing to the status quo and it is possible that the same will happen here."

EU referendum ballot paper
An EU referendum ballot paper. The latest polls show the vote on 23 June is too close to callGetty/AfP

The final YouGov poll showed the race is too close to call, but did put Remain two points ahead, 51% to 49%. Anthony Wells, from the YouGov London office, said that the recent trend had been towards remain and like other referendums in the past there had been a late surge towards the status quo.

"In this poll we asked people who said they didn't know how they would vote which way they were leaning and re-allocated them on that basis, an adjustment that increased the position of Remain by a point, but it is still possible that people will change their mind on the day," he said.

Meanwhile Opinium Research's final poll before the referendum put Leave on 45% and Remain on 44% with Adam Drummond, a polling analyst for the company saying that "undecided voters are holding the balance of the vote in their hands".

Too close to call

John Curtice, the president of the British Polling Council also added to the consensus that the sides were split down the middle, telling BBC's the Daily Politics that Remain had made up ground "but it's certainly not grabbed back all of the ground".

On the final day of campaigning, David Cameron went around the country to make the case for Remain, and was joined by former prime ministers Gordon Brown, John Major and the Liberal Democrat leader Tim Farron and Green MP Caroline Lucas to show off cross-party unity.

Migration has been the focal point of the campaign and there are three million EU people living in the UK who will not be able to vote on Thursday (23 June). Research done by Lebara, a media services provider to the world's migrant community, found that 81% of the UK's migrants would vote for Remain if they were allowed to cast their ballot.

Election analyst Mike Smithson tweeted the latest phone poll results