Facebook's audience has doubled since the start of the year

Facebook, the world's largest social networking site, has created a dual-class share structure to give its owners full control over the company.

A number of privately-owned firms, including Google, have introduced a similar structure before becoming publicly listed companies.

But Facebook said it had no plans to go public "at this time".

The site has more than 300 million monthly users and is now making money, well ahead of schedule.

"We did introduce a dual class stock structure because existing shareholders wanted to maintain control over voting on certain issues, to help ensure the company can continue to focus on the long term to build a great business," said Facebook spokesman Larry Yu.

Analysts said that without the new structure, new shareholders could force through business decisions based on short-term gain rather than long-term interests.