May 5, 2008 - British consumer complaints about environmental claims quadrupled in 2007, according to an annual report from the U.K.'s Advertising Standards Authority.

The watchdog group received 561 complaints about environmental claims on 410 ads last year, compared with just 117 complaints about 83 ads in 2006.

Products or services billed as "carbon neutral" or "carbon negative" generated the most complaints. Absolute claims such as "wholly sustainable" or "100% recycled" raised eyebrows as well.

The huge rise in consumer complaints "suggests greater public scrutiny of advertisers’ environmental credentials," according to the report, and "high levels of awareness of environmental messages [coupled with] confusion about what terms mean" are key contributing factors.

The report also outlines some of the ASA's most buzzed-about rulings, including its decision last November to pull the plug on Shell's controversial "carbon-to-flowers" ad. (An ad billing U.S.-grown cotton as "sustainable" received similar treatment in March.)

Read the full report here.