A judge has barred a former Microsoft executive from working for Google, saying Microsoft has a well-grounded fear that leaked trade secrets could hurt its business.

Superior Court Judge Steven Gonzalez granted Microsoft’s request for a temporary restraining order to prohibit Dr Kai-Fu Lee from performing any duties at the search giant that are similar to those he performed at Microsoft.

"We needed to take this step to protect our sensitive business information and to ensure that Google and Dr Lee honour the confidentiality and non-competition agreements he made when he started working here," a Microsoft spokeswoman said. The judge’s ruling will stand until a hearing on September 6.

Google, which had called Microsoft’s legal case "a shocking display of hubris", downplayed the importance of the ruling, calling it a "temporary measure to maintain the status quo".

Google hired Dr Lee to lead a research and development centre in China. The company said Dr Lee has not disclosed any Microsoft secrets and has now issued proceedings of his own against the software giant.

In court documents, Google said a conversation Dr Lee had with Microsoft chairman Bill Gates suggests the software company is becoming increasingly concerned about Google siphoning away talent - and perhaps intellectual property.

Dr Lee said that in a July 15 meeting, Mr Gates told him, "Kai-Fu, [CEO] Steve [Ballmer] is definitely going to sue you and Google over this. He has been looking for something like this, someone at a VP level to go to Google. We need to do this to stop Google."

Google's lawyer, Nicole Wong, said she was confident the court would eventually side with the search engine. She accused Microsoft of waging an "intimidation campaign".

Dr Lee and Google argue that he is not a search expert and that he had only limited involvement in Microsoft’s China operations since 2000, the year he signed the non-compete agreements.

Dr Lee, most recently a vice president working on speech recognition in Microsoft’s server and tools division, headed up the creation of the company’s research centre in Beijing in the late 1990s and later worked in the MSN search unit.

Microsoft said it would not have hired Dr Lee if he had not promised to honour confidentiality and noncompetition agreements.

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