The Serious Fraud Office (SFO) is looking into whether banks and building societies were told to offer roughly the same amount of collateral, meaning no lender would be singled out for overbidding. This is a situation which would have exacerbated the already frozen financial markets.
The SFO first launched its probe in March, after being handed the results of an inquiry conduct last year by Lord Grabiner QC. Since then BoE officials have attended voluntary "by appointment" interviews with the enforcement agency according to the Financial Times.
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An SFO spokeswoman declined to comment on the report.
"We are committed to providing as much clarity as possible to the public," a BoE spokesman said. "But we recognise that it is the SFO's investigation and it would be inappropriate for the Bank to comment further on the matter at the present time.
It's not the first time the central bank has found itself in the sights of enforcement agencies.
During the fallout from the Libor fixing scandal, it emerged that a phone call had taken place between ex-Barclays boss Bob Diamand former deputy governor Paul Tucker. During the conversation the ex-Bank official could be seen to hint he knows of widespread fixing.