As many as 60,000 people in Hackney who are otherwise eligible to vote could be unable to cast their ballots in next month’s elections unless they register to do so by Monday.

Anyone who hasn’t yet received a polling card in the post must register themselves if they don’t want to miss out on the chance to choose the next Mayor of London, a representative for the European Parliament and successors to outgoing councillors in the Hackney Downs and Stoke Newington wards.

There are at least 11,000 people who pay council tax who aren’t on the electoral register in Hackney, and there could also be as many as 50,000 others listed on a Hackney Council database who are entitled to vote.

Sweeping changes introduced by the government last November mean voters are now individually responsible for registering themselves, a move that has caught many first time voters unawares.

Previously one member of a household could register everyone at the address on one form, but now people must register themselves individually.

The Electoral Commission urged a delay to the Cabinet Office’s constitutional reforms to ensure people were aware of the changes, but they were pushed through with immediate effect.

John Page, from Hackney Unites, a community group that campaigns for social justice, said: “Hackney appears to have been the worst-affected borough in London. Changing the register requires people to be motivated to get on it.

“Some people aren’t aware they may have been taken off and there is the mistaken assumption if you are paying council tax you are automatically on the register.

He continued: “We live in a democracy and people who want to have a say who governs London might not have that opportunity. If people are denied the opportunity to participate in a democratic process, people will resort to other means to express that, which can be quite damaging.”

Hackney Unites teamed up with ice cream firm Ben and Jerry’s earlier this month for a roadshow at the town hall offering free ice cream to encourage people to register.

They will be outside Hackney Community College in Falkirk Street, Hoxton tomorrow from 10am until 1.30pm.

On average four per cent of voters have lost their vote nationally, but Hackney has been one of the worst-hit boroughs.