Almost 800,000 potential voters were deleted from the electoral register under government changes to the system, official figures have confirmed.
The Electoral Commission said about 770,000 names were removed from the register as the government introduced the requirement that people sign up as individuals rather than as households.
Figures from the Office for National Statistics showed the overall register in December 2015 had shrunk by 600,000 names in the preceding 12 months, suggesting a voter registration drive over the same period was successful in getting people to sign up.
But Labour said the huge number of deletions meant hundreds of thousands of people were at risk of disenfranchisement, highlighting a particular problem in university towns and among younger people who are almost eligible to vote.
Overall, the electoral register is smaller by 1.6 million names than at its peak in 2012 when 46.4 million people were on the list.
The government argues that the names removed from the register do not represent real people but are out-of-date entries.
John Penrose, minister for constitutional reform, said: “Councils have only removed ‘ghost’ electors – people who have moved, died or never existed in the first place – so keeping them on the register when we know they shouldn’t be there, and then sending them all poll cards on election day, would be wrong, expensive and increase the risk of fraud.”
However, Gloria De Piero, Labour’s shadow minister for young people and voter registration, said the huge decline in voter numbers was “due to the Tory government’s rushed changes to electoral registration, against the advice of the independent Electoral Commission who warned it would result in thousands of people falling off the electoral register”.
“Today we see that over 600,000 people have dropped off the electoral register in the last year. What’s more, there has been a shocking 40% drop in 16- and 17-year-olds registered to vote,” she said.
De Piero also accused the government of having speeded up the changes to tilt the electoral system in its favour.
“What’s worse is that the government are shamelessly taking this as an opportunity to redraw constituency boundaries based on an electorate that is far lower than it should be,” she said. “This is another example of David Cameron and the Conservative party trying to rig the system for their own political ends.”
Tom Brake, the Lib Dem former deputy leader of the Commons, said the drop was“deeply concerning”.
“The government ignored its own independent regulator of elections, which was clear in its opposition to bringing forward the introduction date of this new system, and Liberal Democrats warned that it would see hundreds of thousands fall off the voting register,” he said.
“There were already millions of people who were not on the register before this move – this has just made that problem worse. Individual electoral registration is a system worth moving to, but it shouldn’t have been rushed and the government should have followed Electoral Commission advice. It is another example of the Tories trying to stitch up the system in their favour.”
The Electoral Commission said it was not possible to estimate the number of eligible electors who were removed from the registers, but it is likely that some of the removed entries related to electors who were eligible to remain registered to vote.
Jenny Watson, the chair of the watchdog, said the official figures indicate “there has been a reduction in the number of entries since the last registers were published under the household system”.