Jason Carter, managing director of Universal McCann Interactive, hit out at online media owners that have failed to adopt traffic measurement systems such as ABC Electronic.
He accused them of lagging behind other sites who provide proof of their popularity with users.
The call comes in the middle of an ongoing debate within the online community as to who should be responsible for introducing an industry-wide measurement tool for internet advertising.
As part of a case study, on behalf of ABC Electronic, Carter challenged a leading technology website to carry out a full audit of their traffic figures, in order to secure a fair portion of UMI's marketing spend on behalf of clients such as Microsoft, MSN, Xbox, More>Than and Intel.
The website, ZDNet, has since pledged to carry out a series of audits with ABCE, triggering an increase in the amount of media spend coming their way.
Carter said: "For such a rapidly growing sector, site measurement has considerably fallen behind where it should be.
"ABC Electronic certification offers a common currency for the planning and buying of online media and is a vital tool for the professionalism of the industry.
"Brands assume it and agencies should demand it. As a result, sites will increasingly miss out if they are unable to supply independent proof and evoke trust for potential advertisers."