The increasingly fraught fight between the two companies comes after Apple said that it would add a new privacy feature that would allow iPhone users to opt out of having their activity tracked between different apps.

Apple has said that the feature is intended to protect its users’ privacy and to encourage developers only to collect the information they need. It has also been supported by civil rights groups including Amnesty International and even competitors such as Mozilla.

But Facebook said in a new blog post – and ads published in major US newspapers – that Apple was deceiving its users. Its supposed concerns about privacy were actually about its own profits, it argued, and it also said that fighting against personalised ad tracking could kill small businesses.

Now Apple has said in a new statement that the argument is about choice, and that users would still be able to opt to have their data tracked if they wanted.

“We believe that this is a simple matter of standing up for our users. Users should know when their data is being collected and shared across other apps and websites — and they should have the choice to allow that or not," Apple said in a statement.

"App Tracking Transparency in iOS 14 does not require Facebook to change its approach to tracking users and creating targeted advertising, it simply requires they give users a choice.”