"Untrue claims" refers to statements or assertions that are not accurate, factual, or in line with reality. It means that the claims being made are not true or right. Full definition
If you make untrue claims about a product or service, this is considered fraud. (businessinsider.com)
They add nothing to any discussion of the scientific merit (or more accurately, lack of any) in Spencer & Braswell 2011, and fabricating untrue claims of «personal attacks» which have never happened only subtracts from all honest attempts at informed, respectful discourse. (judithcurry.com)
Baby Milk Action won a case against Nestle at the Advertising Standards Authority (ASA) in October 2014, after it made untrue claims for its SMA toddler milk in an ASDA customer email. (babymilkaction.org)