Sept. 26 (Bloomberg) -- Washington Post Co. plans to buy Foreign Policy, the magazine focused on global economics and politics, according to a person with knowledge of the matter.

The publisher of the Washington Post newspaper and Newsweek magazine may announce the purchase as early as Sept. 29 and complete it the next day, according to the person, who declined to be identified because the talks are private. The person also declined to discuss the financial terms.

Foreign Policy, based in Washington, has readers in more than 160 countries and is printed in nine languages, according to its Web site www.ForeignPolicy.com. Started in 1970 by Samuel Huntington and Warren Demian Manshel, the magazine is published six times a year by the Carnegie Endowment for International Peace, a research institute focused on international affairs.

Advertising sales at the Post and Newsweek declined more than 20 percent in the second quarter, the company said Aug. 1, reflecting the loss of classified ads and falling magazine readership. Washington Post has increased sales by expanding the Kaplan education services division, which accounts for more than half of revenue.

Foreign Policy had a circulation of 108,106 as of December 2006, according to its Web site. An annual subscription for six print issues costs $19.95, according to the site. The magazine sells advertising in the U.S. and international print editions and on its Web site.

Washington Post Chief Executive Officer Donald Graham wasn't immediately available for comment. Carnegie spokesman Trent Perrotto declined to comment.

Washington Post, whose largest shareholder is Warren Buffett's Berkshire Hathaway Inc., fell $6.42, or 1.1 percent, to $563.58 at 4:01 p.m. in New York Stock Exchange composite trading. The shares have declined 29 percent this year.

To contact the reporter on this story: Sarah Rabil in New York at srabil@bloomberg.net

Last Updated: September 26, 2008 16:23 EDT