The phrase "alleged fraud" means that someone is accused of committing fraud, but it has not been proven yet. It suggests that there are claims or suspicions of dishonesty or deception, but a final determination has not been made. Full definition
One of the requirements for alleging fraud is that your reliance was justified on the alleged misrepresentation. (nar.realtor)
If you think you've been caught up in a sports betting scam you can report it to your state police service which is responsible for investigating alleged fraud. (moneysmart.gov.au)
The lawsuit specifically alleges fraud, negligent misrepresentation and unjust enrichment. (dandodiary.com)