Amazon is catching some flak from music publishers and songwriters over its new service that lets customers store songs and access them from an array of phones and computers.

The National Music Publishers’ Association sent a letter to Amazon on Tuesday outlining its concerns about the digital-music locker service.

“Of specific concern are serious issues, among others, that have been raised regarding lax privacy protections and the failure to include filtering components that would otherwise identify illegal music files placed in a user’s locker,” according to the letter sent by the association’s general counsel, Jay Rosenthal.

The letter said the online retailer needs to clarify its position so that talks can proceed.

Amazon did not respond to a request for comment.