(Postal Service corrects job cuts starting in first paragraph, corrects number of existing mail processing plants.)

Feb. 23 (Bloomberg) -- The U.S. Postal Service, which predicts an annual loss of $18.2 billion by 2015, plans to eliminate 5.4 percent of its workforce by closing almost half of its mail-processing facilities to cut costs.

The service plans to shut 223 of its 461 mail-processing plants by February 2013, Postmaster General Patrick Donahoe said in a telephone interview today. The closings will cut about 35,000 jobs, said David Partenheimer, a Postal Service spokesman.

The closings will save the Washington-based service about $2.5 billion a year, Donahoe said. In September, the agency said it was seeking to save $3 billion a year by closing 252 plants and cutting 35,000 jobs.

Shutting mail-processing facilities is part of a plan to consolidate work and slow mail delivery to save money. The service, which is seeking to end Saturday mail delivery, posted a loss of $3.3 billion for the quarter ended Dec. 31.

The agency has closed 214 mail processing facilities since 2005, including 26 since the September announcement, according to data provided by Sue Brennan, a Postal Service spokeswoman.

--Editors: Andrea Snyder, Steve Walsh

To contact the reporter on this story: Angela Greiling Keane in Washington at agreilingkea@bloomberg.net

To contact the editor responsible for this story: Bernard Kohn at bkohn2@bloomberg.net