Google sued Microsoft yesterday as part of a legal battle over Google's hiring of a Microsoft executive to run its Chinese research center.

Google filed its lawsuit in state court in San Jose, Calif., two days after Microsoft went to court in Seattle to stop Google from hiring Kai-Fu Lee, a Microsoft vice president.

Google's suit argues that under California law, Microsoft can't restrain employees from "choosing where they want to work."

Google hired Lee to open a development center in China to expand its international operations.

It is recruiting Microsoft staff to develop products that challenge Microsoft's Internet and software businesses as the two companies vie for international Web business.

Some 39 percent of Google's $1.38 billion in second-quarter sales came from outside the United States.

Microsoft accused Lee and Google of breaking a confidentiality agreement and a noncompete clause in his contract.

Lee, the most senior executive that Mountain View, Calif.-based Google has snagged from Microsoft, led a group working to improve Web and computer searches.

Microsoft spokeswoman Stacy Drake declined to comment because the company hadn't seen the lawsuit.