JOHANNESBURG: Global giants Barclays, JP Morgan and HSBC are among 17 banks named as part of the two-year investigation.
Banks colluded, using online chat rooms to co-ordinate fictitious bids and offers in order to sway the market, the competition commission says.
It has called for the banks to be fined 10% of in-country annual turnover.
The banks are now likely to face prosecution at the country’s Competition Tribunal over the alleged currency manipulation, which investigators say goes back as far as 2007.
Several banks have already said they will cooperate with the authorities.
Speaking in parliament earlier, South African President Jacob Zuma welcomed the competition commission’s investigation, saying that the government was prepared to act against the distortion of the financial markets “to protect our country’s economy”.
He also reiterated the government’s commitment to establish a state bank, adding that new players must be allowed to enter to diversify the financial sector.