The playing field for Internet content is not level, according to About.com Inc., as long as megaportal Yahoo! Inc. is able to prevent it and other content sites from being listed within its search results.

Scott Kurnit, About.com's (BOUT) chief executive officer, publicly criticized Yahoo! (YHOO) this week for not giving his network enough links in its directory. About.com features more than 700 sites in a variety of topics, though Kurnit said Yahoo! lists very few of them on its site.

"My contention is that any search engine worth its salt would bend over backwards to list those sites," Kurnit told InternetNews.com. "But the fact is that from a listings standpoint they continue, as they always have in our history, to under-include."

Kurnit added private companies have the right to decide what content should be listed on their sites, but Yahoo! is in a unique position, because it is perceived as an objective search service representing all content to be found on the Net.

"They used to exclude our sites as a matter of policy, arguing that as a network, a link to the top of About.com was all that one should get," he said. "They own their business and they have a right to do that. But I think that the public perceives Yahoo! as being a non-biased arbiter of what's good on the Net, and to not include About.com sites is completely inappropriate for a company that claims to do that."

Kurnit said that he has not had problems with other search services, naming America Online (AOL) specifically. He said that 30 percent of About.com's traffic comes from AOL, because it has what he called an "open system." He said other search engines do limit their About.com listings, but not to the extent of Yahoo!.

Yahoo! officials were not immediately available for comment.

The dispute comes as About.com is weighing the idea of spinning off some of its sites as separate units or tracking stocks.