SAN FRANCISCO: Popular messaging app WhatsApp said on Thursday that users around the world had been unable to access its service for a brief period, but that access for its 1 billion daily users had since resumed.

The outage was most acute in northern Europe and Brazil but lasted less than an hour, according to downdetector.com, which tracks disruptions across telecommunications services.

California-based WhatsApp, which Facebook Inc purchased for US$19 billion in 2014, is among the most popular messaging services in the world.