Details including the name, identity card number, age, race and address of people who had signed up between 2009 and 2016 were included in the data dump, technology website Lowyat.net reported.
The data, which appeared to have come from a central database, also contained details of next of kin of those who had registered, it said.
The Personal Data Protection Commission, which is under the authority of the communications ministry, said it viewed the report of the leak "seriously" and had started an investigation.
The data included addresses and identity card numbers. The investigation into the breach is continuing.
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