Autonomy, the UK-based software firm, has been accused by its new US owners Hewlett-Packard of accounting irregularities involving $5bn.

However, the Serious Fraud Office (SFO), which only this week started an investigation over the claims, has admitted it "might" be using an Autonomy product, Introspect, as a document management tool.

SFO said in a statement: "The SFO is keen to ensure that there is now no conflict of interest or perception of such a conflict, and it is obliged as a first step to make inquiries to ensure that it can continue as the investigating body."

The SFO revealed it is participating in an investigation into the software maker’s acquisition by collaborating with the US Department of Justice (DOJ) and UK accounting regulator the Financial Reporting Council over the accusations.

The SFO’s potential conflict is the latest twist in HP’s 2011 acquisition of Autonomy for £7.8bn, which the US firm now blames for a $5bn accounting fraud.

HP alleged that some former members of Autonomy’s management team used accounting improprieties, misrepresentations and disclosure failures to amplify the firm’s actual worth.