The findings revealed that for the first time in the four-year history of the AOP, the number of publishers charging for branded, quality content online has dropped to 37% compared with 63% in 2005.
Online advertising revenue continues to be the top source of income for most media groups, making up an average 41%, according to the AOP survey results.
However, a quarter of the member groups that do charge for online material said they earned them more than £5m in 2005.
Paid-for content contributes 18% of all revenues, while sponsorship made up 9%.
The AOP said that the number of members that said they are unlikely to start charging for online content has also risen from 18% in 2004 to 43% in 2006.
AOP's members include IPC Media, BSkyB, Reuters, BBC, FT.com, The Economist Group, Haymarket, Guardian Unlimited and Which?.
Bill Murray, AOP chairman, said: "While there remains a strong view from consumers that web content must be free, the healthy online ad market has probably convinced most publishers that there is little point in trying to convert customers to paying.
"However, I suspect that within the B2B market and with some of the more interactive high-value consumer content enabled by broadband, we will see long term growth in the number of publishers charging for the best content."
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