A judge in California has tentatively ruled that Apple can force three Mac news sites to reveal the sources of confidential information they gained about an unreleased Apple product.

Lawyers for the Electronic Frontier Foundation, a group that seeks to protect civil liberties related to technology, acted on behalf of the Web sites: Powerpage.org, AppleInsider and Think Secret, but Judge James Kleinberg ruled in Apple's favour.

Lawyer Kurt Opsahl told New York Times he would appeal the ruling.

If the appeal fails Apple will be able to force the three Mac sites to tell them who the source of the information, regarding a product code named Asteroid, was.

Traditionally journalists are not required to reveal the sources of information that is considered to be in the interest of the public. The assumption is that press freedom is necessary if the truth is to be revealed.