The Advertising Standards Authority received 57 complaints about the campaign, which has already been pulled from the air by Reebok.
Most complained that the ad, created by Reebok's US agency NMI Media, glorified gun culture and that it made violence appear acceptable. Others were worried that it would influence younger viewers who might think 50 Cent's violent background was cool and something to aspire towards.
Reebok told the ASA that it took all complaints about its ads seriously, and that it did not back the views of all of the celebrities who endorsed its products. However, it withdrew the ad after noting the offence taken by members of the public.
The ASA upheld both complaints against the ad, saying that the ad suggested that 50 Cent's life was inspirational for the wrong reasons.
In its ruling, it said: "No attempt was made by the advertiser to condemn or express disapproval of the violence portrayed. Although there were some references to the more positive aspects of 50 Cent's life, such as winning an award, this did not appear to result from an attempt by the character to overcome or avoid violence."
It also ruled that the ad could appeal to younger viewers and teenagers, who were susceptible to external influences, especially celebrities. It said the ads were not suitable to be shown at any time.
In the US, where gun crime is far more prevalent, the ad appeared without any complaint -- until word of the UK furore reached gun pressure groups. There have since been moves to have the ad withdrawn there as well.
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