The ruling follows tweets by Manchester United footballer Wayne Rooney and his Arsenal rival Jack Wilshere, posted at the request of the sportswear firm. The Advertising Standards Authority said that the messages did not make clear they were "identifiable as marketing communications". It marks the first time the ASA has acted against a Twitter-based campaign.
The authority said it had intervened after receiving a single complaint earlier this year about two tweets - one from each of the sportsmen posted to their personal accounts.
Nike responded that the presence of its web address alongside a hashtag with its marketing campaign strapline distinguished the tweets from other personal posts by the players. It added that both sportsmen were well known for having being sponsored by the company.
But the ASA said the elements did not make the tweets "obviously identifiable" as adverts, bearing in mind that many Twitter users scroll through a variety of messages at speed. It added that not all of the social network's users would have been aware of the "make it count" campaign, or the footballers' relationship with Nike.
It suggested that in future firms should add #ad or some other clear indication that a message had been paid for.
Source: BBC News
