We have seen the appearance of pop-ups in Safari, on iPads and iPhones, that warn of a virus infection or trouble with your Apple account. The x in the corner of the pop-up does not close it but redirects you to a scam web site.
If one of these pop-ups appears follow these directions;
Do not tap anywhere on the web page or pop-up.
Open the Control Panel by swiping down from the top right corner on later devices or by swiping up from the bottom on earlier devices.
Turn on Airplane mode.
This stops your device from communicating with the
Tap and hold the Tabs icon and close the tab or preferably Close all tabs.
In Settings go to Safari.
Tap Clear History and Website Data.
Make sure that Block Pop-ups and Fraudulent Website Warning are both turned on.
Reopen the Control Panel and turn Airplane mode off.