Investigations found that the employee downloaded the candidate lists of several political parties, Sy Mamabolo, the Chief Electoral Officer of the Electoral Commission of South Africa (IEC), told broadcaster Newzroom Afrika on Tuesday.

Last Friday, the candidate lists of the ruling African National Congress (ANC) and ex-President Jacob Zuma's newly-formed party uMkhonto weSizwe (MK) were leaked on social media, merely hours after the parties submitted them to the IEC.

The leak angered the MK party, which has threatened to take legal action against the electoral body.

President Cyril Ramaphosa on Sunday said he was satisfied with IEC's explanation on the leak and has "confidence in the IEC's ability to deal with all matters that have to do with elections".

Mr Mamabolo says a forensic analysis is under way to establish the ex-employee's motive, but maintains that the incident does not undermine IEC's credibility to hold the country's upcoming May elections.