Royal Bank of Scotland Group Plc managers condoned and participated in the manipulation of global interest rates, indicating that wrongdoing extended beyond the four traders the bank has fired.

In an instant-message conversation in late 2007, Jezri Mohideen, then the bank's head of yen products in Singapore, instructed colleagues in the U.K. to lower RBS's submission to the London interbank offered rate that day, according to two people with knowledge of the discussion. No reason was given in the message as to why he wanted a lower bid. The rate-setter agreed, submitting the number Mohideen sought, the people said.

Mohideen wasn't alone. RBS traders and their managers routinely sought to influence the firm's Libor submissions between 2007 and 2010 to profit from derivatives bets, according to employees, regulators and lawyers interviewed by Bloomberg News. Traders also communicated with counterparts at other firms to discuss where rates should be set, one person said.