The US Federal Trade Commission (FTC) is to turn its attention to advertisers' green packaging claims as it continues its review into whether updated guidelines are required to govern firms' environmental marketing claims.

The watchdog said it would host its second public workshop on possible changes to its so-called Green Guides in Washington on 30 April.

The workshop, which follows a similar event on the marketing of carbon-offset schemes earlier this year, will discuss whether clearer guidelines and definitions are required to support firms' attempts to promote their green packaging claims.

The FTC said that since the Green Guides were last updated in 1998, terms not defined in the guides such as "sustainable" and "renewable" had become an increasingly commonplace feature of many firms' adverts. It added that this trend, coupled with the tendency to use third-party certification schemes to promote green packaging, may have led to "consumer perception and substantiation issues".

It said that the workshop would attempt to tackle these issues by providing a forum to discuss whether an update to the Green Guides is required to better address how new marketing terms surrounding green packaging should be used and substantiated.

The announcement follows attempts by the American Association of Advertising Agencies (AAAA), the American Advertising Federation (AAF) and the Association of National Advertisers (ANA) to head off any changes to the guides.

Last month, the trade groups joined forces to claim that the current guidelines were proving effective and that the FTC should be careful "not to take any action that would stifle the ability or the interest of a company to make positive steps in improving the environment".