China’s blocking of Web sites has embarrassed the International Olympic Committee, but a computer security expert said on Thursday that visitors to Beijing also needed to protect their data from prying eyes.

“People who are going to China should take a clean computer, one with no data at all,” said Phil Dunkelberger, chief executive of security software firm PGP Corp.

Travelers carrying smart cell phones, blackberries or laptop computers could unwittingly be offering up sensitive personal or business information to officials who monitor state-controlled telecommunications carriers, Dunkelberger said.

He said that without data encryption, executives could have business plans or designs pilfered, while journalists’ lists of contacts could be exposed, putting sources at risk.

Dunkelberger said that during unrest in Tibet in March, overseas Tibetan activists found their computer systems under heavy pressure from Chinese security agencies trying to trace digital communications.

“What the Chinese tried to do was infiltrate their security to see who in China the Tibet movement was talking to,” he said.