A former Microsoft Corp. (search) executive who defected to Google Inc. cannot immediately perform the job Google hired him to do, a judge ruled Thursday, saying Microsoft has a well-grounded fear that leaked trade secrets could hurt its business.

Superior Court Judge Steven Gonzalez granted a temporary restraining order barring Kai-Fu Lee (search) from working at Google on any product, service or project similar to those he worked on at Microsoft, including Internet and desktop search technology.

A Google lawyer requested a more specific list of tasks Lee can perform. Microsoft said it would provide the court with its recommended list by Monday.

Microsoft sued Lee and Google last week, claiming that by taking the Google job, Lee was violating an agreement he signed in 2000 barring him from working for a direct competitor in any area that overlapped his role at Microsoft.

Google countersued, arguing that Lee's work for Microsoft had only the slightest connection to the job he was hired to perform at Google.

Microsoft and Google, along with Yahoo Inc. (search), are locked in a fierce battle to dominate Internet searching technology, both online and through desktop search programs. Google has begun offering new services, including e-mail, that compete with Microsoft offerings.