The Advertising Standards Authority (ASA) has launched an investigation into an ad by bookmaker Paddy Power guaranteeing to refund losing bets if South African athlete Oscar Pistorius is acquitted of murder.
46 complaints were made to the ASA about the promotion, which appeared in newspapers and on social media.
A petition on Change.org has also been signed by more than 115,000 people.
A spokesperson for Paddy Power said: "Despite the ASA announcing their investigation, we stand by our decision to run this betting market and publicise it to punters."
More top news
A charity song released in the wake of the Grenfell Tower disaster has shot straight to the top of the singles chart.
Rain in places. Winds strengthen in the north overnight.
Whether it's going to the toilet, paying in a shop or crossing the road, facial recognition technology is changing the way the Chinese live.