Autonomy founder Mike Lynch has launched a US$150mln legal action against Hewlett Packard (NYSE:HPQ) as the fall-out from the disastrous US$11bn acquisition continues to reverberate.

The counter-claim is the latest move in a long-running dispute between the two, with HP recently suing Lynch for US$5.1bn.

HP blamed the accounting practices of Autonomy when it wrote-off three quarters of the 2011 deal’s value just a year later, but these allegations were dismissed by Lynch today.

“Over the past three years, HP has made many statements that were highly damaging to me and misleading to the stock market. 

“Worse – HP knew, or should have known, these statements were false.”

In May, HP set out its case against Autonomy’s former management for the first time, saying it overpaid for Autonomy by at least US$$5bn due to accounting errors.

Lynch added: “We are finally starting to see what really happened with Autonomy. 

“HP’s own documents, which the court will see, make clear that HP was simply incompetent in its operation of Autonomy, and the acquisition was doomed from the very beginning.

“Evidence shows that at the time of the acquisition, HP was in chaos. 

“Before going ahead with the acquisition they discussed firing their CEO. 

“They then tried to abort the deal after closing, ultimately did fire the CEO, and generally fought amongst themselves like cats in a sack, causing Autonomy to disintegrate.

“HP wasn’t misled by us or anyone else – evidence will show they didn’t even read their own due diligence report."

He added that HP’s boss Meg Whitman could explain herself what had happened to a judge, “when we finish this in court once and for all.”