Microsoft filed a lawsuit against Google today asserting that Google hired away a Microsoft executive in violation of a clause in the executive’s contract.

Kai-Fu Lee, who worked at Microsoft since 1998, was hired to lead Google’s China operations.

Tom Burt, deputy general counsel for Microsoft, said Dr. Lee had knowledge of trade secrets pertaining to Microsoft’s search technology and China business strategy.

“We’re thrilled to have Dr. Lee on board at Google and we will defend vigorously against these meritless claims,” Mr. Langdon, a Google spokesman, said in his statement.

There is nothing unusual about companies asking executives and even rank-and-file workers to sign noncompete clauses. At Microsoft, Mr. Burt said, all employees sign an agreement precluding them from giving away trade secrets or working for a competitor for at least a year after leaving the company.