Apple is dictating tougher terms of commerce on its wildly successful mobile devices, demanding a 30 per cent cut on all subscriber" target="_blank" title="n.捐款人；预约者">subscriber content sold directly through its iPads and iPhones.

The new rules, which affect everything from newspaper subscriptions to digital music services, are partly a response to requests from publishers for a system that lets them charge recurring subscription fees, rather than demand a new payment for each individual edition, song or video sold through apps.

Publishers that offer digital subscriptions will have to make the same offer through Apple's App Store. While they can still offer subscriptions via their own websites, they cannot link to that website from the app. The agreement replicates the model Apple introduced this month at the launch of The Daily, News Corp's iPad-only newspaper.

The change is likely to affect the revenues content owners earn from the surging tablet and smartphone market, as Apple will take 30 per cent of any payments it processes.

"Our philosophy is simple - when Apple brings a new subscriber" target="_blank" title="n.捐款人；预约者">subscriber to the app, Apple earns a 30 per cent share; when the publisher brings an existing or new subscriber" target="_blank" title="n.捐款人；预约者">subscriber to the app, the publisher keeps 100 per cent and Apple earns nothing," said Steve Jobs, Apple's chief executive, who has remained closely involved in Apple's activities in spite of being on medical leave.

"All we require is that, if a publisher is making a subscription offer outside of the app, the same (or better) offer be made inside the app, so that customers can easily subscribe with one-click right in the app," said Mr Jobs.