The communications regulator said it had identified three potential areas of concern that might distort competition and harm consumers: transparency of pricing, bundling of airtime and the trading model.
Advertising is the principal source of revenue for the main national commercial public-service broadcaster ITV and regional broadcasters STV and UTV, as well as state-owned Channel 4 and privately owned Five.
After a consultation that runs until July, Ofcom may decide to refer the matter to the Competition Commission for an investigation in the autumn.
Ofcom said poor pricing transparency in the way TV advertising was sold might make it difficult for advertisers to make comparisons between channels and could therefore discourage them from switching spending between TV stations.
The selling of advertising in bundles that straddle peak and off-peak times was also a concern, as it might allow a TV station to use its market strength to achieve higher prices across the schedule than would otherwise have been the case.
Ofcom also questioned why the way TV advertising was bought and sold had changed so little in 20 years, and said it would consider whether there were barriers preventing the trading model from evolving.
