Instagram stopped working properly for many users, with visitors to the site seeing a strange Facebook error message.
The Facebook-owned app appeared to go down in large areas of the UK and Europe, as well as parts of the US, according to an outage map.
The message that greeted users attempting to load the site appeared alongside a Facebook logo. It stated: "Sorry, something went wrong. We're working on it and we'll get it fixed as soon as we can."
Instagram acknowledged an issue with its platform earlier in the day, taking to Twitter to warn users about problems with account follower numbers.
"We’re aware of an issue that is causing a change in account follower numbers for some people right now," the photo-sharing app tweeted. "We’re working to resolve this as quickly as possible."
Instagram has experienced rapid growth in recent years, with an estimated 1 billion monthly active users.
Facebook provoked controversy last month after CEO Mark Zuckerberg revealed plans to merge the messaging services of Instagram, Facebook Messenger and WhatsApp.
A spokesperson for Facebook was not immediately available for comment and it is not clear what caused the outage.
