Facebook Inc confirmed on Friday that some users were having trouble accessing its apps and services, days after the social media giant suffered a six-hour outage triggered by an error during routine maintenance on its network of data centers.

Some users were unable to load their Instagram feeds, while others were not able to send messages on Facebook Messenger.

"We're aware that some people are having trouble accessing our apps and products. We're working to get things back to normal as quickly as possible and we apologize for any inconvenience," Facebook said in a tweet.

People swiftly took to Twitter to share memes about the second Instagram disruption this week.

Web monitoring group Downdetector showed there were more than 36,000 incidents of people reporting issues with photo-sharing platform Instagram on Friday. There were also more than 800 reported issues with Facebook's messaging platform.

Downdetector only tracks outages by collating status reports from a series of sources, including user-submitted errors on its platform. The outage might have affected a larger number of users.

The outage on Monday was the largest Downdetector had ever seen and blocked access to apps for billions of users of Facebook, Instagram and WhatsApp.