Six million Instagram accounts have been exposed online after hackers created a dark web database of personal information, revealing private phone numbers and email addresses.

The scale of the hack on the photo-sharing site emerged after the Instagram account of singer Selena Gomez was compromised last week. UK security researchers discovered hundreds of contact details on the dark web of celebrities including Emma Watson, Taylor Swift and Harry Styles.

In addition to leaking the details of hundreds of A-listers, hackers created an online database where cyber criminals could access private user details for $10 per search.

Instagram initially said a "low percentage" of accounts had been affected, although the hackers claim they have details on as many as six million users, the Daily Beast reported.

Instagram has since responded with its advice on how to protect accounts and report suspicious activity.