According to a statement by the Hong Kong Monetary Authority today, its investigation over benchmark interest rate manipulation found six traders of UBS attempted to rig the rates between the years 2006 and 2009.

The discovery, said the Hong Kong regulator in the statement, was due to the hundred internal chat messages that contain change requests by traders who worked at UBS for the bank's submissions to set the country's Interbank Offered Rate. The regulator said that it has asked UBS to put the traders involved in the attempted manipulation under disciplinary action as there has been a negligible impact due to the attempted fixes.

At press briefing today, HKMA deputy chief executive Arthur Yuen said, "When they discovered the requests, they did not draw that to our attention. They did not report the cases to us. We equally find that unacceptable."

Bloomberg said that the probe into potential misconduct started in December 2012 with UBS. The Hong Kong regulator widened the prove and included eight lenders six months later as similar crackdowns were observed in the US, UK, Japan and Singapore. Total fines imposed worldwide due to the benchmark rate manipulations have reached $6 billion as of December last year.

Hong Kong-based spokesman Rob Stewart for UBS told Bloomberg in an emailed statement, "We are pleased that the investigation of the HKMA returned the same results as our own internal investigation -- no collusion among banks and no noticeable impact on the fixing of Hibor. (The bank had) taken appropriate steps to incorporate the HKMA's suggested improvements."

HKMA sais today that UBS is no longer considered to be a reference bank for Hibor in October 2010 and has not made any submissions since. The regulator also added that the six traders who were involved in the attempted rate-rigging has left the bank.