Jeremy Corbyn said government plans that would demand voters provide photo ID at polling stations would “disproportionately” discriminate against ethnic minorities.
The Labour leader said Conservatives were targeting people unlikely to vote for them.
“These plans are clearly discriminatory and a blatant attempt by the Tories to suppress voters, deny people their democratic rights and rig the result of the next general election,” he said.
“The people that the Tories are trying to stop voting will be disproportionately from ethnic minority backgrounds, and they will disproportionately be working class voters of all ethnicities.”
A Labour Party spokesman said there was only one conviction for in-person voter fraud at the 2017 election and 3.5 million UK citizens did not have any form of photo ID.
Research from the independent Electoral Commission showed women were less likely than men to have ID, and black people were less likely than white people to have a driving licence.
A Cabinet Office spokesman said showing ID was a “reasonable and proportionate” way to protect elections from fraud.
“Voter ID is one part of a body of work this government is delivering to give the public confidence that our elections are secure and fit for the 21st century,” he said.
Conservative Party chairman James Cleverly accused Mr Corbyn of “sowing the seeds of division”.
“If anything, tougher checks against electoral fraud will protect the democratic rights of all communities,” he said.