Today HP filed a lawsuit claiming that Oracle had breached an agreement to support the Itanium microprocessor.

The lawsuit was filled at thge Superior Court of the State of California, County of Santa Clara.

Oracle decided in March to discontinue its support for Intel's Itanium processors, saying Intel made it clear the chip was nearing the end of its life.

The lawsuit follows a "formal legal demand" letter that HP sent to Oracle last week to force the software maker to reverse its decision to discontinue software development on Intel Itanium microprocessor.

"It just takes a few minutes to read the early drafts of the agreement to prove that HP?s claim is not true," Oracle said in a statement. "What is true is that HP explicitly asked Oracle to guarantee continued support for Itanium; but Oracle refused, and HP?s Itanium support guarantee wording was deleted from the final signed agreement."

Oracle added that in September of 2010, HP had asked Oracle for a long-term commitment to support Itanium. "At that time Oracle did not know that there was a plan already in place to end Itanium's life. Oracle did not learn about that plan until six months later, in March 2011. We believe that HP specifically asked Oracle to guarantee long-term support for Itanium in the September of 2010 agreement because HP already knew all about Intel's plans to discontinue Itanium, and HP was concerned about what would happen when Oracle found out about that plan," Oracle said.

HP and Oracle became rivals after Oracle's purchase of Sun Microsystems pushed it firmly into the server hardware market, in which it previously cooperated with HP.

Oracle hired former HP chief executive Mark Hurd last year after he left HP amid questions over his relationship with a female contractor. HP filed a trade secrets lawsuit against Hurd related to the Oracle hire, which was soon settled.

Tensions between the two companies rose further when HP hired former SAP AG chief executive Leo Apotheker as its CEO. During his time at SAP, Apotheker was locked in an extremely bitter copyright infringement battle with Oracle.

After Apotheker joined HP last year, Oracle charged Apotheker with overseeing an "industrial espionage scheme" at SAP, centered on stealing Oracle's software.

"What we know for certain is that Ray Lane and HP's current board members and Leo Apotheker and HP's current management team now know full well that Intel has plans in place to end-of-life of the Itanium microprocessor. Knowing this, HP issued numerous public statements in an attempt to mislead and deceive their customers and shareholders into believing that these plans to end-of-life Itanium do not exist. But they do. Intel?s plans to end-of-life Itanium will be revealed in court now that HP has filed this utterly malicious and meritless lawsuit against Oracle," Oracle's said.