The European Central Bank (ECB) website has been hacked, with attackers stealing personal information.
The organisation added that no internal systems or market sensitive data were compromised.
"The database serves parts of the ECB website that gather registrations for events such as ECB conferences and visits. It is physically separate from any internal ECB systems," said the Frankfurt-based central bank for the 18 nations that share the euro.
The German police has launched an investigation into the security breach but the bank did not specify when the theft is believed to have happened or how much money was demanded.
An ECB spokeswoman said the attack was identified after an anonymous email was sent to the ECB seeking financial compensation for the data.
The bank is contacting those whose data was stolen, and passwords have been changed, according to the spokeswoman.