A fan's misjudged Facebook post could get companies in trouble under new rules governing social media advertising.

The Advertising Standard Authority has introduced its first ''guidance'' for social media advertising, as companies increasingly turn to Facebook or Twitter to promote their brand.

The guidance states companies are responsible not only for their own online content but any user-generated content, such as Facebook posts or tweets, directly under their control.

This means a company could be censured for offensive or misleading content posted by a third-party on its Facebook page.

Authority chief executive Hilary Souter said if the content was on a controlled platform, such as a Facebook page, the company was responsible.

''If you are a brand page where the advertiser has control then you have a responsibility to manage that content.''

While each case would be treated on its own merit, the Authority would take a particularly dim view of any offensive or misleading content solicited by the advertiser, such as a competitions, she said.

The guidance does not cover any activity outside a company's control, such as reposting advertisements with added offensive comment or fan pages.

''This will not cover 'I like nike' or 'I like coca-cola' Facebook pages.''

Souter said the Authority had dealt with some social media complaints with all but one related to company generated content.

Last month, a complaint was lodged against Hell Pizza for hosting a Facebook ''confessional'' in which one user described scenes of sexual abuse.

The claim was settled with Hell Pizza making a $10,000 donation to Wellington Rape Crisis.

The Authority has also reprimanded two bars which promoted drink specials and heavy drinking on their Facebook pages.

The guidelines follow a landmark decision by the Australian Advertising Standards Bureau decision, in which it deemed companies responsible for moderating comments of their Facebook page.

The decision related to complaints against Fosters for its Victoria Bitter-branded Facebook page, on which users discussed heavy drinking and made derogatory sexual comments.

- © Fairfax NZ News

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