WhatsApp, the online messaging service, went offline on Wednesday evening, leaving millions of users worldwide "in turmoil".

The Facebook-owned service went down at around 9pm BST, affecting users in the UK, US, Australia and Brazil, among other countries. It returned at around 11.20pm.

It was unclear what caused the issues with the hugely popular online messaging service.

A spokesman for WhatsApp said: "Some people have had trouble accessing WhatsApp for a short period today.

"We apologise for the inconvenience."

WhatsApp, which is reportedly planning a major update, did not comment on the cause of the problem, but complaints posted on social media quickly made the service the top trend in the UK on Twitter.

Many users reported being able to open the app, but not able to connect to its servers, making it impossible to send or receive messages.