The UK’s Financial Services Authority, and the Swiss Financial Market Supervisory Authority, issued statements today, confirming recent media speculation that such enforcement action against the Zurich-listed bank was in the offing.

“We will continue to fully cooperate with our regulators. Immediately after the unauthorised trading incident, the group executive board thoroughly investigated the incident and implemented measures to better protect our firm from unauthorised activities,” UBS said in a statement.

“Our ability to disclose further details relating to the unauthorised trading incident and the measures we are taking is limited by the fact that regulatory investigations and criminal proceedings are ongoing. This does not prevent us from taking further decisive action to improve our operational risk controls,” it said.

UBS is due to issue quarterly results on 7 February.

The trading loss, which had been disclosed by the UBS investment bank at a time when the Swiss firm had seen a recovery in its fortunes after the 2008 credit crunch, led to the resignation of chief executive Oswald Grübel, to be eventually replaced by senior UBS manager Sergio Ermotti. UBS has completed its own internal investigation. London police have charged Kweko Adoboli, the trader arrested in the matter, with fraud and false accounting. He denies the charges.

“The FSA has now commenced a formal enforcement investigation against UBS and is in close contact with FINMA which has also commenced enforcement action against UBS,” the FSA said in a statement.