(Reuters) -- Regulators in Britain and Switzerland may take steps against bank UBS for shortfalls in oversight that allowed an alleged rogue trader to run up a huge loss, the Wall Street Journal reported on Sunday, citing sources familiar with the matter.

In September, UBS said a London-based trader had run up a $2.3 billion loss. British authorities have charged trader Kweku Adoboli with fraud and false accounting. The scandal eventually prompted Chief Executive Oswald Gruebel to resign.

That trading scandal came after UBS had to take government aid during the financial crisis, after suffering huge losses on risky U.S. subprime debt.

UBS has carried out its own internal investigation into the trading affair and several employees -- including the head of the equities business -- quit.

Swiss regulator FINMA and Britain's Financial Services Authority may penalize the bank for a failure of internal controls that allowed the loss to take place, the Wall Street Journal reported citing unnamed people familiar with the matter.

It said the investigations could be finished by the middle of February, although enforcement measures could take longer.

FINMA spokesman Tobias Lux declined to comment. A spokesman for UBS said he was not yet able to comment.

(Reporting by Catherine Bosley; Editing by Marguerita Choy)