Facebook Inc said on Friday its services were being affected by a number of issues, after nearly a million people across the world reported problems with its photo-sharing app Instagram.

“Multiple teams are working on it (the outage), and we'll update you when we can,” Facebook's gaming unit said in a tweet.

It tweeted about an hour later that the service had been restored, asking users to report to Facebook if they continued facing issues.

The outage of Instagram, WhatsApp and Facebook Messenger was reported by people across the world, The Independent reported. After less than an hour, users reported the services had started to function normally.

"Thanks for your patience, that was a long 45 minutes but we are back!" WhatsApp tweeted after the app was restored.

Earlier, tens of thousands of users took to Twitter to complain about the outage, with #whatsappoutage trending in many countries, including India and Pakistan. The top two trends in Pakistan were #whatsappdown and #facebookdown.

Users reported seeing error alerts when they opened the apps — which share common technology under Facebook — and were unable to send or receive messages.

Outage tracking website Downdetector.com showed there were nearly one million incidents of people reporting issues with Instagram, while nearly 20,000 users posted about problems with WhatsApp on the website.

The major outage was reported at around 1730 GMT, according to Downdetector. However, shortly after 1800 GMT, several WhatsApp users said on social media that they were able to again send messages on the app.

Instagram also came back after about an hour.

Downdetector tracks outages by collating status reports from a series of sources, including user-submitted errors on its platform.

Facebook platforms have been hit by a few significant outages in recent years. As the three platforms have become more closely intertwined, the outages have become larger, since an issue on one of the apps usually means that all three go down, according to The Independent.

A number of Pakistani politicians and celebrities reported facing problems with WhatsApp on Twitter.

"What happened to WhatsApp?" tweeted PPP Senator Sherry Rehman.