Reports of an item-duplication exploit have caused Blizzard to close servers.

Blizzard’s Korean branch officially announced the planned downtime on the local forum yesterday. There’s currently no news on exactly how long these updates are going to take.

If there is indeed an item duplication exploit then it could cause some problems when Diablo’s real-money auction house launches, which is supposed to be happening very soon.

Blizzard is in the process of making use of their authenticator completely obligatory if players wish to use their Battle.net account for real-money.

"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," explained Blizzard community manager "Kaivax" 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."

If players have Battle.net Balance in their account then they’ll be able to use it without an authenticator. Players will need to use their authenticator in order to add any new balance.

Mobile authenticators are available free on iPhone, iPod touh, Blackberry, Android and Windows Phone.