Bet365, Coral and Totesport have been told off by the UK advertising watchog for using images of US Masters and US Open champion Jordan Spieth to promote betting.

Under the UK advertising code it is illegal to use people aged under 25, or someone who appears to be so, to play a “significant role” in promoting gambling and betting.

Images of Spieth, who is 22, featured in Twitter campaigns for the bookmakers.

Coral said the photo of Spieth was used to illustrate the odds available rather than promote specific bonus offers, but it had made changes to ensure that similar tweets complied with the code.

Bet365 said its tweet reported on a major sporting event and therefore did not breach the code.  Totesport gave the best answer. They said Spieth was neither a young person nor vulnerable and the and did not show him gambling or indulging in juvenile or loutish behaviour. So that told them.

The Advertising Standards Authority said the tweets were designed to promote each bookmaker’s brand and referred to future sporting events on which the public might consider betting.

“We considered the tweets were directly connected with the supply or transfer of goods,” said the ASA. “We therefore concluded that the ads were irresponsible and breached the advertising code. The ads must not be shown again in their current form.”