The Government is to enact an "emergency" law tomorrow to extend the deadline for voter registration by 48 hours that could have a huge impact on the result of the EU referendum.
Cabinet minister Matt Hancock said people should carry on applying to register to vote after the official Electoral Commission website crashed one hour-and-45 minutes before last night's midnight cut-off.
Hancock told Parliament a massive 214,000 people an hour were trying to register - much higher than the 74,000 peak at last year's general election - when the site came down.
He later tweeted confirmation and the deadline to apply to register is now midnight tomorrow (June 9).
Despite claims from some supporters of 'Brexit' that the move would prompt a legal challenge the official Vote Leave campaign did not oppose the move - saying people will "only have one chance to vote on sharing free movement of people with Turkey".
Earlier, Tory MP Bernard Jenkin, who is campaigning to Leave, warned the move to extend the deadline could face a judicial review, and urged the Government to offer only a few hours grace.
The move is highly significant.
Those not registered to vote are most likely to be young people - in turn the group most likely to vote to Remain. With polls on a knife-edge - the most recent giving Leave a narrow lead - the extension could swing the result.
Answering an urgent question in the Commons, Hancock said: "We are looking at legislative options, including secondary legislation. We need to make sure we get the details of any emergency legislation exactly right since we have to pass it at pace."
David Cameron urged people to carry on registering to vote on Twitter - and renewed the call at Prime Minister's Questions
Hancock had urged people to "register now, today" as they will be "captured by the system".
Acknowledging the legal threat in the Commons, the minister added: "Then we have the legal question of whether captured applications can be eligible for June 23. That is the issue we will deal with potentially in legislation."
He detailed the surge in interest (see video above):
"To give the House a sense of the scale of demand the peak before the General Election was 74,000 applications per hour, and last night the system processed 214,000 per hour at its peak before it crashed.
"Many who applied to register after 10.15pm were successful but many were not, and the problems with the website were then resolved around the deadline at midnight
"We are urgently looking at all options and talking to the Electoral Commission about how we can extend the deadline for applying to register to vote.
"The website is now open and working and we strongly encourage people to register to vote online. Anyone who is already registered does not need to submit an application."
But Jenkin hit out at the Government for being "ill-prepared", and warned how the cut-off point was set so the final register could be published six days before the referendum and challenged if necessary.
He added: "Any idea of re-writing the rules would be complete madness, and make this country look a shamble. Will he keep these things in mind or risk a judicial review as a result."
Some among the Leave campaign were even suggesting the website had been crashed deliberately.
However, Tory Cabinet minister Michael Gove, chairman of Vote Leave, gave the move his support.
"People will only have one chance to vote on whether they share free movement of people with Turkey, so the more people who register to vote on June 23 the better and we welcome the extension of the registration deadline.
"It is particularly important given how few young people normally vote and I hope that this election will be different."