text: Premier League stars including Steven Gerrard, Theo Walcott and Phil Jones could face an advertising watchdog probe they plugged an Adidas  sale on Twitter. Manchester City's David Silva and Everton's Phil Jagielka were also among around a dozen players sponsored by the firm who urged millions of followers to buy the knock-down goods. This comes amid mounting concern that celebrities and sports stars are cashing in by turning Twitter into an advertising platform. The players posted messages within minutes of each other yesterday, with Arsenal forward Walcott tweeting: 'For 25 hours you can get 25% discount on Adidas.co.uk if you use 'friendsoftheo'.' Premier League stars including Arsenal forward Theo Walcott (pictured) could face an advertising watchdog probe they plugged an Adidas sale on Twitter . Silva tweeted: 'Who is up for 25% savings on @adidas products? Click here to find out more! #friendsofdavid.' Guidance from the Advertising Standards Authority states that when there is payment and control from an advertiser, the sponsored tweet should be obviously identifiable. British celebrities have been advised to include the word 'ad' or 'spon' to show if something is an advert or sponsored. The watchdog has previously banned a Nike campaign featuring tweets from Wayne Rooney, one of its brand ambassadors, because they were not clearly identified as promotional messages. Players including Steven Gerrard (pictured) and Everton's Phil Jagielka were  among around a dozen players sponsored by the firm who urged millions of followers to buy the knock-down goods . It was the first UK company to have a Twitter campaign banned, after the ASA ruled in 2012 that the use of the  personal accounts of footballers broke the rules. The Manchester United striker, who has more than 11 million followers, tweeted: 'My resolution — to start the year as a champion, and finish it as a champion...#makeitcount gonike.me/makeitcount'. A tweet from Jack Wilshere said: 'In 2012, I will come back for my club — and be ready for my country.#makeitcount.gonike.me/Makeitcount'. Both footballers were banned from repeating the messages and Nike was warned about ensuring all Twitter advertising is easily identifiable. England footballer Phil Jones and Manchester City's David Silva posted messages within minutes of each other . But another one of Rooney's tweets was said to have not breached advertising rules because its language was markedly different from the footballer's usual Twitter messages. This tweet said: 'The pitches change. The killer instinct doesn't. Own the turf, anywhere. @NikeFootball #myground.' The Advertising Standards Authority has not yet received any complaints about the promotional tweets for Adidas. But a spokesman said: 'If we receive complaints that tweets have broken rules, we will investigate. 'Marketing communications must be obviously identifiable as such. 'If any social media account (including celebrity twitter accounts) are tweeting ads and it's not clear from the context that these are marketing communications then they need to be labelled as an ad.' Some fans saw straight through the players' Adidas tweets, with GX Blue ‏tweeting: 'I bet you David Silva didn't write that tweet himself!!' A spokesman for Adidas said: 'To our knowledge, there have not been any complaints about the tweets and we have not been contacted by the ASA with regards to this matter. 'This is a promotion we run several times a year in collaboration with our players to offer fans a sizeable discount and the tweets are clearly identifiable as marketing communication.'
target: Top footballers are under fire for using Twitter to promote an Adidas sale .
  Players including Steven Gerrard and Theo Walcott  could face a probe .
  Dozen Premier League stars posted messages within minutes of each other .
  Watchdog advises celebrities to use the word 'ad' or 'spon' if its an advert .