Macau’s government has pledged to crack down on unauthorized outdoor advertising promoting gambling services.

On Wednesday, officials from Macau Economic Services (MES) revealed that they had investigated 316 suspected instances of illegal gaming-related advertising in the last six months of 2014. Only 14 of these ads had been approved by the Civic and Municipal Services Bureau (IACM), the body responsible for issuing ad permits.

Compounding matters, those ads that had been approved – many of them promoting online gambling sites – were apparently okayed in error. MES deputy director Tai Kin Ip said these ads had been “deceptive enough to have cheated the IACM authorities for the go-ahead.”

That does little to assuage the concerns of local taxi drivers, some of whom have been threatened with prosecution for displaying the mistakenly approved ads on their vehicles. Critics have voiced concern that the overlapping mandates of MES and IACM have led to confusion as to what’s legal and what isn’t, which prompted the government to issue some clarification on its advertising laws.