NEW YORK (Reuters) - The St Louis Cardinals have agreed a deal to get three-times All Star outfielder Matt Holliday from the Oakland A's in return for three minor league prospects, Major League Baseball website mlb.com said Friday.

The 29-year-old Holliday, who can be a free agent at the end of the 2009 season, was batting .287 with 11 homers and 54 runs batted in for Oakland after a slow start this season.

The Cardinals, who lead the tight NL Central by 1.5 games over the Cubs and Astros, were sending third baseman Brett Wallace, a 2008 first-round draft pick, Triple-A pitcher Clayton Mortensen and Double-A outfielder Shane Peterson to the A's.

(Writing by Larry Fine in New York, Editing by Justin Palmer;)