HP said in a legal filing Thursday that the U.S. Department of Justice is investigating its $10.3 billion acquisition of enterprise search company Autonomy, which HP alleges inflated its value through accounting tricks.

HP also said it has provided information to the U.K.'s Serious Fraud Office and the SEC related "to the accounting improprieties, disclosure failures and misrepresentations at Autonomy" prior to the acquisition, according to HP's 10-K filing with the U.S. Securities and Exchange Commission (SEC).

The company said last month it had shared its allegations with those agencies, urging them to open civil and criminal investigations. The DOJ advised HP on Nov. 21 of its investigation, the filing said.

HP disclosed an $8.8 billion write-down in November, around $5 billion of which was attributed to accounting improprieties by Autonomy. The write-down was for impairment of goodwill, a term covering intangible assets such as the value of a brand and good customer relations.

Autonomy's founder, Mike Lynch, who left the HP in May, has fiercely contested HP's claims. He published a stern rebuke on Friday.

"We continue to reject these allegations in the strongest possible terms," Lynch wrote. "Autonomys financial accounts were properly maintained in accordance with applicable regulations, fully audited by Deloitte, and available to HP during the due diligence process."

Lynch wrote that he and his Autonomy colleagues have not yet been contacted by regulators. "We will cooperate with any investigation and look forward to the opportunity to explain our position," he wrote.

HP looked closer into the Autonomy acquisition, completed in October 2011, after a senior member of its former management team came forward following Lynch's departure.