Diablo 3 servers in Asia are currently offline following reports of item-duplication exploits.
Blizzard's Korean arm initially announced the downtime on the game's local forum yesterday. Subsequent updates announced that more time would be needed to complete the work. No estimate has been given for when the game's servers will return.
An exploit allowing users to duplicate items would have serious implications for the game's real money auction house, due to start trading imminently.
Blizzard has announced tougher security measures ahead of the launch, including the need to use an authenticator attached to a Battle.net account.
"Starting today, in order to add to your Battle.net Balance, players will be required to have a Battle.net Authenticator or Battle.net Mobile Authenticator attached to their Battle.net account," Blizzard community manager "Kaivax" wrote on the official Diablo 3 forum.
"For clarity, this means you'll need to have an Authenticator to add to your balance via Battle.net Account Management or to send the proceeds of your real-money auction house sales to your Battle.net Balance."
Players who previously added Battle.net Balance to their account will be able to use it without attaching an Authenticator. Any new balance added will require an Authenticator, however.
Mobile Authenticator apps are now freely available for iPhone, iPod touch, Blackberry and Android devices.