The UK's Serious Fraud Office today said it had closed a long-standing investigation into how the Bank of England held auctions to boost lending during the global financial crisis. 

"After a thorough investigation the SFO has concluded that there is no evidence of criminality in relation to this matter," the fraud office said in a statement.

The probe had lasted two and a half years and had been triggered following an inquiry by the Bank of England itself. 

The SFO had in December 2014 launched an investigation into money-market auctions held by the central bank to ensure commercial banks were not left short of cash.

This had been a particular concern during the financial crisis when the value of assets were slashed and cash liquidity levels tightened.

"The director of the Serious Fraud Office today closed the SFO's investigation into the conduct of liquidity auctions held by the Bank of England during the financial crisis in 2007 and 2008," today's statement said.

"The focus of the investigation was whether assistance had been provided to certain financial institutions to enable them to bid successfully for the available funding, to the possible detriment of other institutions," it stated. 

"The Bank of England referred this matter to the SFO in November 2014, following its own internal investigation, and the investigation was opened the following month," it added.