The popular messaging app LINE has hundreds of millions of users across Asia and the company has urged people to change their passwords yesterday.
A Line spokesman says more than 300 cases of unauthorised access have been confirmed between late May and June 14, including three that involved cash trades resulting in financial loss.
“We are cooperating with police in investigating the cases, and we are calling for users to change passwords,” he said.
The spokesman said the accounts were hacked “presumably after shared passwords with other online services were leaked somewhere else”.
He said that the company believed all of the breaches occurred in Japan.
Another spokeswoman for the company stressed that Line’s servers had not come under attack.
“Line’s system itself has suffered nothing abnormal. It is not that our system was hacked,” she said.
A police spokesman says the case is under investigation.
Line was set up in 2011. The app now has more than 400 million users, mainly in Japan and mainland Asia, and is growing fast.
The service lets users make free calls, send instant messages and post photos or short videos, combining attributes from Facebook, Skype and the messaging application WhatsApp.
Line has forged heavyweight partnerships with football clubs FC Barcelona and Real Madrid, brands such as Coca-Cola and tennis star Rafael Nadal.
FC Barcelona, for instance, has a home page on the app which has millions of “friends”.
One of Line’s main selling points is its “stickers” which are funny, cartoon-like figures that users can post to friends.