Taking aim at the way news is spread across the Internet, The Associated Press said on Monday that Web sites that used the work of news organizations must obtain permission and share revenue with them, and that it would take legal action against those that did not.

A.P. executives said they were concerned about a variety of news forums around the Web, including major search engines like Google and Yahoo and aggregators like the Drudge Report that link to news articles, smaller sites that sometimes reproduce articles whole, and companies that sell packaged news feeds.

They said they did not want to stop the appearance of articles around the Web, but to exercise some control over the practice and to profit from it.

The group’s new stance applies to thousands of news organizations whose work is distributed by The A.P., as well as its own material, but the debate about unauthorized use has focused on newspapers, which are in serious financial trouble, and which own The A.P. The policies were adopted by the A.P. board, composed mostly of newspaper industry executives.