An investigation sparked by complaints about the AFL's controversial variable pricing ticket scheme, introduced this year, found football fans were misled about the cost and benefits of their membership.

The Australian Competition and Consumer Commission said the AFL neglected to tell members they would be forced to pay extra fees to attend certain matches.

The breach related to membership advertising that did not include additional costs for "reserve" games. Extra fees paid by fans ranged from $8.50 and $39 for general admission AFL club members and $7.50 for AFL members.

ACCC chairman Rod Sims said the regulator had concerns with the behaviour of half of the league's 18 clubs, but would not name them.

"They were advertising their memberships and saying you were entitled to so many games and then in February the policy changed to variable pricing, but many of them just kept on advertising the same thing when it was no longer accurate," Mr Sims said.

"The reason we put them on alert is that there have been concerns for some time about lack of clarity in the way the AFL and some of the clubs advertise."

In May it was revealed the ACCC was investigating the AFL's variable ticket pricing structure after members reported paying extra fees to attend the round five clash between Geelong and Hawthorn.

On Thursday the ACCC said the AFL had removed all reserve classified games from round 15 onwards. Some clubs had also made changes to promotions on their websites after the regulator intervened.

"The AFL and clubs are now on notice that the Australian Consumer Law applies to them, and that the ACCC expects disclosure of these types of additional costs to be made in a way which is clear, prominent and immediately proximate to any representations regarding the price and benefits of membership," Mr Sims said.

An AFL spokesman said it would work with all clubs to "ensure greater clarity in marketing communications around member entitlements". "The AFL fully cooperated with the ACCC's inquiries and will take on board the ACCC feedback," he said.

The ACCC said it would monitor the issue and consider enforcement action against clubs or the league if more complaints were received.