The UK Advertising Standards Authority (ASA) is looking into a promotional Twitter campaign from Snickers to see if it breached trading standards.

The campaign prompted complaints over the brand, owned by Mars, hiring B and C list celebrities to tweet about its nutty chocolate bar. UK model Katie Price and England international footballer Rio Ferdinand were among the celebrities who took part.

Their followers were initially confused when the pair began posting a series of uncharacteristic tweets; budget Kardashian Katie Price musing on the potential economic effects of quatitative easing, and football hard-man Ferdinand tweeting about taking up knitting.

They went on to explain that they weren’t quite themselves because they were hungry, then posted an image of themselves with a Snickers bar, looking very pleased with their chocolaty, nutty treat, along with @Snickers, and the hashtags #hungry and #spon.

Around 90 minutes later, @SnickersUk tweeted an explanation, naming the celebrities involved.

The stunt, which coincides with a TV advertising campaign the brand is running, left some followers disgruntled. One reply to the £130,000 a week professionals footballer Ferdinand read, “Do you really need the money that badly?” with another adding “I’m not here to be advertised at”.

However, as brands and marketers strive to find new ways of reaching the masses of people on twitter, many would argue that the campaign orchestrators at Mars are probably wearing wry, satisfied smiles today, not even counting the substantial publicity the promotion has generated.

Ferdinand, a prolific Twitter user, has almost 2m followers, while Price has more than 1.5m. Other celebrities involved in the stunt included singer Cher Lloyd with 900,000, UK boxer Amir Khan, 460,000 and former England cricket legend Ian Botham, with more than 45,000.

@SnickersUK, by contrast, boasts 825.

The ASA will examine whether the tweets were misleading by not explicitly stating that they were promotional; it will look at whether the #spon hashtag marked them clearly as marketing communication.

This is the first time the ASA has been prompted to investigate a specific case involving Twitter since it assumed responsibility of social media marketing oversight in 2010. The UK Office of Fair Trading, the previous incumbent of the role, had previously warned brands that promotional tweets must be clearly labelled.