Local and international banks have been accused of rigging the price of South Africa’s currency, the rand, by the country’s competition watchdog.
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.
The South African rand has nearly halved in value against the US dollar over the past five years, as the country goes through an economic crisis.
Major international banks have had to pay out billions of dollars in fines since a global scandal in 2013 over the rigging of foreign exchange markets.