Facebook is back in court over allegations that founder and chief executive Mark Zuckerberg stole the concept of the site from ConnectU, a service run by his Harvard classmates.

The two parties originally went to court last summer over the case, which involves allegations of breach of contract, copyright infringement and fraud.

The suit alleged that Zuckerberg had taken the idea for Facebook from fellow students Cameron and Tyler Winklevoss after Zuckerberg was hired to work on HarvardConnect, a university networking site which would later become ConnectU.

ConnectU alleges that Zuckerberg took the stolen idea and code and proceeded to build what would later become a multi-billion dollar social networking success.

Facebook later countersued, claiming that ConnectU had attempted to illegally access its databases to retrieve company data.

A settlement was first reached in February, but ConnectU has since asked for the case to be reopened, claiming that it has new evidence and that the original agreement should be voided.

The case took an unexpected turn yesterday, when the presiding judge decided to close the hearing to the public.

This fuelled speculation that ConnectU's new evidence includes logs of instant messages involving Zuckerberg which Facebook seeks to keep confidential.