(CNN) A 12-year-old girl was among three minors caught gambling at a casino in Sydney, Australia, regulators said Saturday. According to Liquor & Gaming New South Wales (NSW), the state regulator, The Star Sydney -- among the largest casinos in the country -- has been fined about $64,500 (90,000 Australian dollars) for that instance as well as two other cases of minors gambling and being served alcohol. Surveillance footage released by the regulator showed the pre-teen being sneaked into the casino by her mother, who held an exit door open for her to avoid security.