The BBC reported Monday that they have uncovered an audio recording between two employees of Barclays that suggest the BOE was exerting pressure on banks to reduce the Libor rate.
In a statement seen by CNBC, a Bank of England spokesperson has said Libor was not regulated in the UK at the time, but the bank was now assisting the Serious Fraud Office (SFO).
"LIBOR and other global benchmarks were not regulated in the UK or elsewhere during the period in question.
"Nonetheless, the Bank of England has been assisting the SFO's criminal investigations into LIBOR manipulation by employees at commercial banks and brokers by providing, on a voluntary basis, documents and records requested by the SFO," the statement read.
The central bank also said it would not publish documents related to the investigation until the SFO's investigations on manipulations of LIBOR and other benchmark interest rates had ended.
According to the BBC, the 2008 recording reveals Barclays manager, Mark Dearlove, instructing colleague and Libor submitter Peter Johnson, to lower his Libor rates:
"The bottom line is you're going to absolutely hate this... but we've had some very serious pressure from the UK government and the Bank of England about pushing our Libors lower."
Mr Johnson resists the instruction but is then, according to BBC interpretation, reminded of top-down pressure from Dearlove:
"The fact of the matter is we've got the Bank of England, all sorts of people involved in the whole thing... I am as reluctant as you are... these guys have just turned around and said just do it."
Libor is a daily rate set at 11:45 a.m. after several banks submit a price at what they believed they could borrow money from other banks at. The rate is then finalized as an average of the various submissions.
Barclays has already paid heavy fines after admitting that between August 2005 and May 2008, some of its traders called counterparts at competing banks and colluded to submit Libor rates that benefited trading positions.
Other banks that have reached settlements with U.S. authorities in connection with Libor rate-rigging scandals include UBS, Royal Bank of Scotland, Deutsche Bank and ICAP.