Gorenjska banka recorded an increased number of simultaneous accesses to the on-line content, which caused a short-term overload of the communication channels.
At that time, users were not able to access the bank's website and its on-line services, and the use of e-mail was also limited, the bank told Delo.
It added that the access to all services was provided again in a very shot time and that the attempted attack had not affected the security of information, personal data or assets of its clients.
The newspaper Dnevnik meanwhile unofficially reported today that an attempted hacker attack was also recorded in the Maribor-based NKBM bank, adding that the attackers had failed to break into the system and that the clients' money was safe.
The bank's website was inaccessible for half an hour, with the bank citing technical difficulties as the official reason provided, the paper said.
The national cybersecurity centre SI-CERT and the Bank Association of Slovenia (ZBS) confirmed that attacks were detected last week in certain banks and savings banks, adding that there was no danger to personal data and assets of clients.
"SI-CERT received in recent days reports of attempts of distributed denial of service (DDoS) attacks in some banks and banks and savings banks with the purpose of extortion", the institutions said in a joint press release.
"The attackers sent an extorting message to banks and savings banks demanding ransom in return for ceasing the attack," the release adds.
The situation is under control and the attacked banks are "exchanging information and are closely cooperating with SI-CERT and the Slovenian police in containing and investigating the incident."