The government has announced that prisoners serving less than four years will be eligible to vote.
But the Cabinet Office statement said all offenders sentenced to four years or more would automatically be barred from registering to vote.
The decision comes after a European court ruling which the government is obliged to implement.
Meanwhile a man serving life for raping and murdering a seven-year-old niece lost an appeal over his right to vote.
Under the changes, the sentencing judge will be able to remove the right to vote from some prisoners sentenced to less than four years.
Mark Harper, Minister for political and constitutional reform, said proposal was “not a choice, it is a legal obligation”.
“We are ensuring the most serious offenders will continue to be barred from voting.
“If the government failed to implement this judgement, we would not only be in breach of our international obligations but could be risking taxpayers’ money in paying out compensation claims,” he said.
Five years ago, the European Court of Human Rights (ECHR) ruled the UK’s long-standing voting ban was unlawful.
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