(Web Desk) - Spotify has launched an outspoken attack on new transaction fees of up to 27% being levied by Apple in the US.
Apple announced it would permit app developers to sell products in places other than its own store - but only if they still paid commission.
Spotify said that was "outrageous" and accused Apple of "stopping at nothing" to protect its profits.
It is urging the British government to prevent similar fees being levied in the UK. Apple has been approached for comment.
The firm introduced the fees in the US as a result of a long-running legal battle with Fortnite developer Epic Games.
The court found in favour of Apple on multiple issues, but it fell foul of a law by not allowing app developers to tell people about other ways of paying, including through links that bypass Apple's own App Store payment system.
Apple charges the biggest developers a 30% fee to use this system, though smaller developers pay around 15%, and 85% of developers don't pay a fee at all.
As a result of the ruling, Apple has introduced a new set of rules in the US which will allow people to subscribe to services without using its system, but it will charge developers up to a 27% commission to do so.
According to court documents filed by the firm, it said the commission charge was compliant with the court ruling, adding that App Store developers benefit from Apple's services.
"All App Store developers - including those who place buttons or links with calls to action in their apps - benefit from (among other things) Apple's platform integrity," it said in the filings.
It also listed other benefits developers receive, including: "marketing and external advertising, and a safe environment for users to download and purchase apps and in-app content."
Spotify has reacted with fury, saying the policy "flies in the face" of the US court's attempt to enable greater competition.
"Once again, Apple has demonstrated that they will stop at nothing to protect the profits they exact on the backs of developers and consumers under their app store monopoly," it said in a statement.