The move follows claims that City executives at three other banks have been put on leave as regulators in the UK, Switzerland and the US examine whether there was collision between the financial institutions over rate setting.
Citigroup, JP Morgan and Standard Chartered are the firms whose staff have reportedly been put on leave, although there has been no accusations of any wrong doing by them.
A spokesman for RBS, which is thought to have been contacted by regulators, would not comment last night.
Barclays has launched its own internal probe into its foreign exchange trading.
The Financial Conduct Authority is currently inquiring into whether traders used instant messages services to fix rates in a similar way to the Libor [London interbank offered rate] scandal.