Amazon has said its sales of MP3s have increased since the arrival of its Cloud Drive.
Last month, Amazon revealed the online storage service and player, which lets users play their music collection from any computer as well as some mobile devices.
The announcement angered music labels that believed the storage and streaming service was breaking copyright and required an additional licensing agreement.
In response, Amazon's music team has reportedly sent an open letter to music firms, claiming the Cloud Drive service had boosted MP3 sales - although it hasn't said by how much.
The letter - seen by Billboard - stressed that Amazon doesn't think its online storage service requires a deal with music firms.
"There has also been speculation that we are looking for licenses for Cloud Drive and Cloud Player," the letter said, according to Billboard. "We are not looking for licenses for Cloud Drive or Cloud Player as they exist today - as no licensees are required."
"Cloud Player is a media management and play-back application not unlike Windows Media Player and any number of other media management applications that let customers manage and play their music," it adds. "It requires a license from content owners no more than those applications do. It really is that simple."
However, Amazon said it would be looking to cut licensing deals soon, as new features are rolled out. The letter said there would be "potential enhancements to Cloud Drive and Cloud Player that would require licenses, including serving different customers with a single copy and save on the efforts by customers to upload music to the Cloud Drive".
This article originally appeared at pcpro.co.uk