More than 436,000 people took advantage of the Government's controversial decision to extend the voter registration deadline by 48 hours after the website crashed.

More than half of the late sign-ups were aged under 35, fueling accusations that David Cameron tried to 'rig the referendum' by reopening the registration website, with polls showing younger voters are more likely to vote for Britain to stay in the EU.

Brexit campaigners accused the Prime Minister of 'desperate cheating' by extending the deadline for 48 hours, despite the website being down for just 105 minutes on Tuesday night.

MPs rushed through an emergency law yesterday to approve the extension but Brexit campaigners reacted angrily, questioning why registration was reopened for a whole two days.

The 436,344 people who have signed up since the website was reopened after the initial deadline is far higher than the estimated 50,000 people who attempted to register during the 90 minutes when the website was down, which the Cabinet Office blamed on 'unprecedented demand'.

More than half of the late sign-ups were aged under 35, fueling accusations that David Cameron tried to 'rig the referendum' by reopening the registration website, with polls showing younger voters are more likely to vote for Britain to stay in the EU

Some 238,903 voters applied to register online on Wednesday, joined by 191,508 on Thursday, and another 5,936 people using paper forms.

Over the last four days nearly 1.2 million registered for a vote in the June 23 referendum.

The deadline to register to vote was pushed back by MPs after thousands of voters were prevented from registering by the original deadline of midnight on Tuesday when the website failed.

According to a live monitoring site there was a flurry of activity on the registration service webpage in the minutes before midnight on Thursday.

The monitor showed there were just under 5,000 people using the service at 11.55pm and more than 3,000 still on the site after the deadline had passed.

Pro-Brexit Tory MP Michael Fabricant said the decision to extend the deadline by two days to compensate for 105 minutes 'seems like desperate cheating' by the Government.

191,508 signed up for a vote in the EU referendum on Thursday, and another 5,936 people using paper forms

Fellow Leave Tory campaigner Bernard Jenkin said the move by the Government was on the 'cusp of legality'.

Brexit campaigners are considering making a legal challenge of the 48-hour extension - and potentially the outcome of the June 23 vote.

The millionaire Ukip donor and co-chairman of the Leave.EU Brexit campaign group signalled he would bankroll a judicial review of the move if the result is close enough to be affected by the extra sign-ups, many of whom are expected to be in favour of staying in the EU.

The insurance tycoon Mr Banks said: 'For the Government to alter election law during an election period is absolutely unprecedented and unconstitutional.

'This isn't some democratic initiative, it's a desperate attempt by the Establishment to register as many likely Remain voters as possible before polling day.

'Terrific efforts have been made to target young people, thought to be more sympathetic to the EU, while older voters who backed Remain in 1975 but have grown heartily sick of the bloc after 40 years of broken promises were given a body swerve.'

He added: 'Taken together, we believe that the above constitutes a clear attempt to rig the referendum or, at a bare minimum, to load the dice.

'We believe it is unconstitutional at best and have been advised that with legitimate cause we could challenge this extension.

THE DANCE STUDENT WHO MISSED DEADLINE BY JUST SIX MINUTES Student Jordan Parker tried for more than two hours to register before finally managing to do so six minutes past the deadline after the website started responding. The dance student called the website crash 'ridiculous' and said he had a friend in a similar situation. He added: 'I'm pleased with Cameron's comments but it has to be done. They are left with no other choice. It isn't just me, there are thousands of people. 'It's ridiculous they are saying they didn't expect the overwhelming numbers of people using the website. Concert websites run fine, this is a lot bigger than a concert. It is the biggest vote of my generation. 'I am hopeful it will now mean I can vote.' The De Montfort University student said he tried to register at university last week, but did not have access to his National Insurance number until he arrived home on Tuesday night. He said: 'This is the earliest I could get back and try to register.' Advertisement

'We are therefore considering all available legal options with our legal team, with a view to potentially launching a judicial review now and after the outcome of the referendum on 23 June.'

During the 24 hours leading up to the original deadline, more than half a million people applied to register, causing a system overload.

Downing Street said 214,000 people were trying to use the www.gov.uk/register-to-vote website between 9pm and 10pm on Tuesday, but it was not known how many were prevented by the overload from registering before the midnight deadline.

Some of those attempting to register were met with the message: 'Sorry we are having technical problems. Please try again in a few moments.'

The Government held emergency discussions with the Electoral Commission to extend the deadline to register to vote to the end of Thursday amid demands from senior figures including Labour leader Jeremy Corbyn and Liberal Democrat chief Tim Farron.

Earlier this week pro-Brexit Tory Sir Gerald Howarth criticised the extension, adding that voters had only themselves to blame if they missed out after leaving registration to the last minute.

He told the Commons: 'People have had months and months in which to register and ... if they left it to the last minute and all tried to register yesterday, that's their fault.

'We should not change our regulations in the middle of a very important referendum campaign simply to suit those who haven't organised their personal affairs well enough to secure their registration in good time.'

Despite the large numbers of applications, not all are fresh registrations as the figures include those who may be unaware of the fact they are already signed up to vote, as well as those who are ineligible.

This was seen during last year's general election when around five million applications to register to vote were made in England and Wales between January 1 2015 and the deadline on April 20 - but the number registered to vote increased by only 1.35 million.

The EU voting farce continues as ministers admit 5,000 polling cards have been sent to non-eligible EU nationals and under-18s

Ministers admitted today that the number of polling cards sent to non-eligible EU nationals and under-18s was 5,000 - 40 per cent higher than they previously said.

But Cabinet Office minister Oliver Letwin insisted the problem has now been 'cured' as he told MPs the Government will ensure the issues will not be repeated at future elections.

Last week the elections watchdog said 3,462 polling cards had been issued in error - EU nationals and even a 17-year-old girl among those sent voting slips despite being barred from taking part in the June 23 referendum.

Reports have emerged of referendum polling cards being sent to EU citizens who are not eligible to vote in the poll on June 23

EU nationals living in the UK are allowed to vote in council and European elections – but they are barred from voting for MPs or in the referendum.

But numerous examples emerged last week of EU nationals being sent polling cards by their local councils.

Officials revealed a 'glitch' in election software called Xpress used by several councils failed to properly record the nationality of some voters.

WHO IS ALLOWED TO VOTE IN THIS MONTH'S REFERENDUM? The people on Gibraltar have been given a vote in this month's referendum despite not usually taking part in general elections Laws implementing this month's referendum based the franchise for the historic vote on who can vote in general elections. This includes all British and Irish citizens but excludes EU nationals who are living in the UK via free movement rules. EU nationals are allowed to take part in local and European Parliament elections. The rules create surprising anomalies - such as Nick Clegg's wife, the Spanish lawyer Miriam González Durántez, who cannot vote. In addition, the European Union Referendum Act allows peers to vote and also extends the franchise to the population of Gibraltar who, given their close proximity to Spain, will be enormously affected by the result. Advertisement

The Electoral Commission said none of the affected voters would be allowed to take part on polling day.

Mr Letwin confirmed the scale of the problem as the Commons pushed through emergency legislation to extend the deadline to register to vote in the EU referendum to the end of Thursday.

The Government registration website crashed close to the original deadline of midnight on Tuesday, resulting in thousands of people being unable to submit their applications.

David Cameron caused outrage by deciding to reopen voter registration for 48 hours, despite the website only being down for 105 minutes.

The move allowed 240,000 people to sign up for a vote yesterday, over half of whom are under the age of 35.

With research showing younger voters are more likely to back Britain staying in the EU, some Brexit campaigners have suggested the Government is trying to 'rig the referendum' by extending the deadline.

Addressing concerns over polling cards being sent to ineligible voters in today's debate, Conservative MP Henry Smith told Mr Letwin: 'In terms of the checking of those who are eligible to vote, with large numbers seeking to be on the electoral roll, I from my constituency have had a number of reports of EU nationals being sent postal voting papers and also, just last night, somebody calling me to say their daughter who was 17 years old had received voting papers.

'What sort of assistance will be provided to electoral services officers and returning officers to ensure the vote is secure in that sense?'

Mr Letwin, in his reply, said: 'There has been, in a few cases, a problem with the issue of votes to people who were not eligible for voting.

'That problem has now been inspected and cured, and we need to make sure that in future elections it doesn't happen.'

Conservative former cabinet minister Liam Fox, a leading Leave campaigner, asked Mr Letwin: 'You say this problem of ballot papers being issued to those not eligible to take part in this election has been identified and cured.

'Can you therefore give us an idea of the scale of the problem? How many of these wrong ballot papers were issued?'