Labour reportedly plans to introduce automatic voter registration (AVR) if elected next week.
The party's manifesto said it would ‘improve voter registration' and electoral officials have told a national newspaper the pledge relates to plans for people to be added to the electoral roll by default, although a Labour source denied the party was committing to the policy.
It comes after the Welsh Government announced plans to introduce AVR last year.
Some 5.1m people remain unregistered to vote despite a surge in applications after the General Election was announced.
Research by the Electoral Commission last year found young people and private renters continue to be less likely to be correctly registered to vote.
Labour has also committed to addressing ‘inconsistencies' in voter ID rules, citing the issue of veteran cards not being accepted.