More than 10,000 voters have disappeared from the electoral roll in Brighton and Hove during the past year.

Figures show that 12,500 voters have fallen off the electoral register, meaning 10.5% of 2014’s electorate could be barred from the ballot box.

Brighton and Hove is among several university cities highlighted for poor registration rates under updated electoral regulations introduced last June.

Cardiff’s roll lost 8.9% of voters, while Newcastle and Nottingham lost 9% and 6.4% respectively.

The city council has written to every student and reminded them to check they are included on the electoral register by April 20.

Penny Thomson, chief executive at Brighton and Hove City Council, said: “The way people register to vote has changed. Under the new Individual Electoral Registration each individual is responsible for registering themselves instead of the former system where the ‘head of the household’ registers everyone living at the property.”

Universities can no longer register blocks of students at their halls of residence under Individual Electoral Registration. This means hundreds of voters who might have been covered by a single registration under the old regulations must now sign up separately.

Green MP for Brighton Pavilion Caroline Lucas called on the Government to invest more in targeting unregistered residents.

She said: “These figures confirm our worst fears – a frightening number of people have fallen off the register, which shows the Government’s approach is undermining democracy.”

Peter Kyle, Labour parliamentary candidate for Hove said: “Young people are getting a raw deal as it is, with youth services slashed, lack of quality employment opportunities and hikes to university fees. So to be disenfranchised in this way will be the final straw for many.”

Labour leader Ed Miliband accused deputy prime minister Nick Clegg of delivering the “final insult” to young people, as more than one million people nationally have fallen off the electoral roll.

Conservative MP for Hove Mike Weatherley insisted the changes would safeguard electoral integrity and noted there was still time for people to register.

He said: “The principle aim of the change in registration rules was to tackle electoral fraud.”