Data Protection Commissioner Billy Hawkes has called on Apple to explain the reasons for having a position-logging feature on its iPhones and iPads.

Security researchers have found that the phone keeps track of the users' movements - and saves every detail of it to a secret file on the device which is then copied to the owner's computer when the two are synchronised.

Speaking on Morning Ireland, Mr Hawkes said buyers should have been made aware of the feature.

This week the company said that net profit rose 95% in the second quarter of its fiscal year to $5.99bn.