Royal Bank of Scotland (RBS) says it is investigating the conduct of more than 50 past and present staff and suspended bonuses for 18 people as part of its forex scandal inquiry.

In an update today on the accountability review, initiated after it was among five banks fined a total of £2.6bn by regulators last month, RBS said six senior employees had been placed in a disciplinary process.

Three of those members of staff were currently away from their desks, pending continuing investigations, RBS said.

The bank was handed fines totalling £400m in November after it settled separate cases with US regulators and the City watchdog, the Financial Conduct Authority.

Settlement notices showed market rules were breached over years through collusion between foreign exchange traders.

The RBS statement on its continuing review said: “These investigations are complex, and the bank is striving to complete the review as soon as possible.

“The bank will provide a further update when the review is complete, which we expect to be in the first quarter.”

It added: “Currently the unvested awards of 18 individuals remain suspended pending the outcome of the review.

“The awards will not vest until the process is complete.

RBS Head of Conduct and Regulatory Affairs, Jon Pain, who is leading the review said: “We are undertaking a robust and thorough review into the actions of the traders that caused this wrongdoing and the management that oversaw it.

“This is a complicated process but also an essential one in order to identify culpability and accountability for this unacceptable misconduct.

“To be clear, no further bonus payments will be made or unvested bonus awards released to those in scope of the review until it has concluded and its recommendations have been considered by the Remuneration Committee and the Board Risk Committee.

“There is no place for any misconduct at the RBS we are building. We want to get these things settled so we can put these issues behind us and get on with rebuilding trust in this bank.”

The Chancellor confirmed plans this week to amend legislation so traders who rig rates in future could face jail terms of up to seven years.