Clifford Chance is advising Autonomy founder Mike Lynch against allegations of financial impropriety and misrepresentation made by Hewlett Packard (HP), which acquired Lynch's software company last year for $11bn (£6.8bn).

The magic circle firm also confirmed it is advising other former members of Autonomy's management.

HP made the allegations in a press statement on 20 November, as it announced an $8.8bn (£5.5bn) write-down related to Autonomy in the fourth quarter of its 2012 fiscal year.

It attributed more than $5bn (£3.1bn) of the write-down to "accounting improprieties, misrepresentation and disclosure failures discovered by an internal investigation by HP and forensic review into Autonomy's accounting practices prior to its acquisition".

HP also announced it had referred the matter to the US Securities and Exchange Commission and the UK's Serious Fraud Office for civil and criminal investigation.

In a letter to the HP board on 27 November, Lynch rejected the allegations of impropriety, saying "it was shocking that HP put non-specific but highly damaging allegations into the public domain without prior notification or contact with me, as former CEO of Autonomy".

Lynch, who left HP earlier this year, said: "Autonomy's finances, during its years as a public company and including the time period in question, were handled in accordance with applicable regulations and accounting practices. Autonomy's accounts were overseen by independent auditors Deloitte LLC, who have confirmed the application of all appropriate procedures including those dictated by the International Financial Reporting Standards used in the UK."

Days after HP's announcement last month, San Diego-headquartered Robbins Geller Rudman & Dowd filed a class action on behalf of HP shareholders, alleging the company and certain of its officers and/or directors violated federal securities laws.

HP did not comment on which firms it had instructed in the wake of its announcement.

Gibson Dunn, Freshfields Bruckhaus Deringer and Drinker Biddle advised HP on last year's acquisition of Autonomy, with HP's board of directors taking advice from a London-based team at Skadden Arps Slate Meagher & Flom.

Slaughter and May and US firm Morgan Lewis & Bockius advised Autonomy on corporate and antitrust matters respectively.

Suggestions in the media that law firms involved in the original deal could be exposed to reputational damage or litigation as a result of HP's claims have been dismissed by corporate and tax lawyers.

One corporate head of a top City firm said: "As far as the role of lawyers is concerned, it would be unusual for the law firms to be involved in the due diligence, so I would be very surprised if there was any reputational or litigation brought to the law firms."