The website of the European Central Bank (ECB) has been compromised by hackers, resulting in the theft of email addresses and other contact data.

The ECB claims that no sensitive data was lost as the databases containing the contact details is physically separate from any internal ECB systems.

A spokesperson for the ECB told IBTimes UK that 20,000 email addresses were stolen by the hackers in the attack. It is still not clear who the perpetrators were and an investigation by police in Frankfurt, where the ECB is based, is currently underway.

"The theft came to light after an anonymous email was sent to the ECB seeking financial compensation for the data," a statement on the ECB website read.

"While most of the data were encrypted, parts of the database included email addresses, some street addresses and phone numbers that were not encrypted. The database also contains data on downloads from the ECB website in encrypted form.

"The ECB is contacting people whose email addresses or other data might have been compromised and all passwords have been changed on the system as a precaution.

The ECB says it takes data security "extremely seriously" and said the German police had begun an investigation. It added that its own data security experts have "addressed the vulnerability".

In 2013, audits carried out by internet security firm Check Point on 150 financial organisations revealed that 88% had experienced a data loss incident, up from 61% in 2012.

"The European Central Bank was clearly unaware it had been infiltrated as it first came aware when the attackers issued a ransom for the data they had obtained," said Keith Bird, a security pecialist at Check Point.

"With the pace of attacks increasing it highlights the need for multiple layers of defence, including encryption for all data, to mitigate the risks of intrusion and data theft."