HBOS is understood to be at the centre of Lloyds's admission it is one of several banks being investigated by US authorities for Libor manipulation.
Yesterday, Lloyds said in a regulatory filing it had received requests for information as part of the investigation looking into alleged manipulation of Libor, according to the Daily Telegraph.
It said it is co-operating with regulators including the US Commodity Futures Trading Commission and European Commission.
HBOS is the main target given its near collapse in late 2008 as it lost access to wholesale funding markets, according to sources with knowledge of the investigation.
A spokesman for Lloyds declined to comment on whether HBOS was the centre of the inquiry, the Telegraph reports.
HBOS merged with Lloyds TSB in January 2009 to form Lloyds Banking Group.
Barclays and Royal Bank of Scotland have already said they are part of the investigation and HSBC staff are also understood to have been questioned.
Last month, three European asset management firms accused banks including Bank of America Corp., JPMorgan Chase & Co., HSBC Holdings Plc, Barclays Bank Plc and Credit Suisse Group AG of conspiring to manipulate Libor.
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