Among meanings for preposition per, wiktionary.org includes "in accordance with [ e.g.] I parked my car at the curb per your request." It defines as per as a preposition meaning "Consistent, or in accordance, with." Taking wiktionary as a guide, one can use either form with little difference in meaning, but I think some people will object to such use of per and others to such use of as per. My preference is for per because most uses of as per that I've heard seem pompous and verbose.