
Nigel Gwilliam, media and emerging technologies consultant at the IPA, said many leading UK media owners have refused to sign up to the Digital Trading Standards Group, an initiative that verifies third-party content.
"That’s a real danger and a real point of weakness," Gwilliam said, because media owners that have not signed up, such as The Guardian and Time Inc, could run an ad on an inappropriate third-party site.
Gwilliam, speaking at a Group M event on brand safety, added: "If they are packaging up off-site inventory, it is essential the trust they command as brands is matched with policies and processes governing how they source that off-site traffic. There is no independent oversight of that currently."