Britain's Serious Fraud Office (SFO) has launched a probe into the 2008 investment deal between Barclays and Qatar's sovereign wealth fund, the bank announced on Wednesday.
Barclays confirmed in a statement that the SFO -- an independent government department -- had commenced an investigation into payments "under certain commercial agreements between Barclays and Qatar Holding LLC".
The Financial Services Authority (FSA) regulator revealed in July it was investigating fees paid by Barclays to Qatar during the 2008 credit crisis.
Qatar invested more than £2 billion ($3.1 billion, 2.5 billion euros) into the bank in June 2008, and five months later it raised a further £6.8 billion from a group of Middle Eastern investors, allowing it to avoid being semi-nationalised.
British and US regulators fined Barclays £290 million ($453 million, 369 million euros) in June after the bank admitted that it attempted to manipulate the Libor and the related European Euribor rates between 2005 and 2009.
The fallout risks becoming much wider, however, with analysts claiming that the lender could face massive lawsuits, since mortgage rates passed onto customers were influenced by Libor rates.