Microsoft stepped its up rivalry with Google on Tuesday, filing a lawsuit against the search company over the hiring of a former Microsoft employee.

The software giant alleges that Kai-Fu Lee, who joined Google on Tuesday to spearhead new research and development efforts in China, is violating a ‘non-competition’ agreement signed when he was hired by Microsoft. Lee had been corporate vice-president of Microsoft's Natural Interactive Services Division until Monday.

"We are asking the court to require Dr Lee and Google to honour the confidentiality and non-competition agreements he signed when he began working for Microsoft," the company said in a press statement.

"Dr Lee … has direct knowledge of Microsoft’s trade secrets concerning search technologies and China business strategies. He has accepted a position focused on the same set of technologies and strategies for a direct competitor in egregious violation of his explicit contractual obligations."

Among other things, Microsoft is asking the court to prevent Lee and Google "disclosing or misappropriating" any of Microsoft's trade secrets or proprietary information.

Microsoft is also requesting that the court prohibit Lee or anyone at Google from luring other Microsoft employees away from the company.

In a statement, Google executives said Microsoft's claims are "completely without merit" and that the company plans to fight the suit.

"We're thrilled to have Dr Lee on board at Google," the company said. "We will defend ourselves vigorously against these meritless claims and will fully support Dr. Lee."

Google and Microsoft have become increasingly heated rivals in the areas of email and desktop search, and Microsoft CEO Steve Ballmer has repeatedly expressed his intentions to unseat Google from its dominant position in the search-engine space.

Indeed, at the annual Microsoft Research Faculty Summit on Monday, Bill Gates referred to Google as a "faddishly hot" company, suggesting that the vendor is merely a flash in the pan.

It's not uncommon for technology companies to require employees to sign so-called ‘non-compete’ agreements that prohibit them from working at a competitive company or luring other employees away from their previous employers for a certain time period after they leave.
According to a Google press statement, the company aims for Lee, who is known for his work in the areas of speech recognition and artificial intelligence, to expand Google's recruitment, research and development efforts in China. The vendor expects to open its new China facility in the third quarter of this year.