The ANC in the Eastern Cape has discovered "ghost members" on its membership books, Business Day reported on Friday.
Provincial secretary Oscar Mabuyane told Business Day the party had discovered that databases from public and private institutions had been used to get people's details to enrol them.
Some were not even aware they had been made African National Congress members.
The culprits who tampered with the membership forms also deposited the R12 joining fee so they could be deemed to be in "good standing".
Mabuyane said this was discovered when the membership register was checked ahead of branch meetings to discuss the upcoming national elective conference in Mangaung.
The matter was still under investigation, he said.