Facebook Inc's WhatsApp messenger suffered a temporary outage in India and many other countries, according to reports from multiple users on Facebook and Twitter on Friday.

Users in countries ranging from Brazil and Russia to Vietnam and Myanmar reported on social media that WhatsApp was down in their countries. The extent of the outage and the reasons for it were not immediately known.

'Whatsappdown' was the top trending item on Twitter in India, which is WhatsApp's biggest market with about 200 million of its billion-plus users. It was also a top trending item on Twitter in Pakistan, Britain, Germany and many other countries.

Users reported WhatsApp, the world's most popular messaging service, had begun to gradually function again about 30 minutes after initial complaints of an outage appeared on social media.

A spokeswoman for Facebook in Singapore said the company was still investigating the matter.

Independent websites monitoring outages of popular social media services via online conversations and Twitter messages report regular outages for WhatsApp, often one every few weeks, but these are typically brief and confined to certain geographies.

WhatsApp has faced similar widespread outages this year, including for several hours in May.

WhatsApp is used by more than 1.2 billion people around the world and is a key tool for communications and commerce in many countries. The service was acquired by Facebook in 2014 for $19 billion.

Reuters