The increasingly acrimonious spat over Hewlett-Packard's acquisition of Autonomy has stepped up a gear after an HP shareholder filed a lawsuit citing Big Four audit firms KPMG and Deloitte, claiming they failed to spot serious issues in Autonomy's accounts.

HP's board of directors, officers, and ex-executives were also named in the lawsuit, which was filed in San Jose, California on Tuesday, for alleged breaches of duty and negligence.

HP's shares hit a 10-year low last week following its $8.8bn (£5.4bn) write-down on the acquisition, which it blames on improper accounting at Autonomy.

Meg Whitman, HP's chief executive said the company relied on audits carried out by Deloitte UK of Autonomy when making its decision to shell out $11.1bn for Autonomy.

She said the company also relied on KPMG's audits of Deloitte's work.

KPMG said in a statement "we can say with confidence that we acted responsibly and with integrity", and that it had not been tasked with carrying out any audit work or to oversee the Deloitte audit work subject to the accusations. KPMG said it delivered only limited services unrelated to Autonomy's audit and that it acted with responsibility and integrity.

Reuters reports that Deloitte had added nothing further to last week's statement, that it was not responsible for due diligence on the Autonomy acquisition. Deloitte added that it had no knowledge of any accounting improprieties or misrepresentations in Autonomy's financial statements and that its last audit opinion on Autonomy was for the year ended December 2010.

The lawsuit, filed by Philip Ricciardi, an HP shareholder since 2007, also named as defendants Whitman, HP CFO Catherine Lesjak, and former HP CEO Leo Apotheker.

It claims their inadequate due diligence had caused billions of dollars of harm to HP and made it overpay for Autonomy.