A lapse in security for Facebook has proved embarrassing for the social networking site coming only days after privacy options were beefed up.

For a brief time on Monday, strangers were able to view personal photos posted on Facebook user's profile pages, completely circumventing the recent upgrade to the site's privacy controls.

Discovered by Byron Ng, a Canadian computer technician and verified by the Associated Press, the loophole allowed Ng to look at private photos of Paris Hilton, while the AP viewed the personal photo album of co-founder Mark Zuckerberg.

A Facebook spokesperson has said the bug was fixed within an hour of them being alerted: "We take privacy very seriously and continue to make enhancements to the site".