(Reuters) — Facebook Inc said in a blog post Monday it will begin rolling out a notification for iPhone users globally about how data is used for personalized ads, in an attempt to get ahead of upcoming Apple Inc privacy changes that Facebook says will hurt its advertising business.

The full-screen prompt will ask Facebook and Instagram users to allow their app and website activity to be used for personalized ads and to “support businesses that rely on ads to reach customers.”

The social media giant has been waging a public fight against Apple’s plan to ask iPhone users whether to allow apps to track them across other websites and apps, warning that Apple’s notification “suggest there is a tradeoff between personalized advertising and privacy,” and will harm small businesses that rely on Facebook ads.

Apple said its pop-up privacy notifications will start appearing on most iPhones in the next few months. (Reporting by Sheila Dang Editing by Alistair Bell)