Australia's oldest commercial radio station has been dropping advertorials into the 9am to 1pm timeslot, a trial of the new format it wants to introduce across the entire station from September 1.

The changes have caused disquiet in the industry. It's attracted attention from both the Australian Communications and Media Authority as well as from competitors wary of losing advertising. ACMA has been skittish around radio advertorial since the cash for comment scandal in 1999, in which key hosts were given cash payoffs to mention advertisers favourably.