The official website of Slovenia's president and of other state bodies have been targeted in distributed denial-of-service attacks (DDoS), but the authorities say the servers have not been breached.

The president's website was the first to be affected. It was down down for several hours on 27 March as the authorities preventively blocked malicious traffic.

The national Computer Emergency Response Team (SI-CERT) blocked the attack in the evening, but media reports said the attack continued overnight at other websites.

According to the news portal N1, the websites of the National Assembly and the government were temporarily inaccessible from abroad as malicious traffic was preventively blocked.

Uroš Svete, the head of the Government Information Security Office, said there had been no unauthorised entry into the system. He would not comment on who was behind the attack.

The authorities would not say which sites apart from the president's were affected.

It described the attack as "coordinated flooding with requests aimed at overloading the server and making it difficult to access."

Such DDoS attacks have been monitored by the response centres of the EU and NATO member states ever since the start of the Russian invasion of Ukraine, SI-CERT said, noting that standard counter-measures are used in such situations.

SI-CERT has not provided further details, but the 24ur news portal reported that a Russian hacker group had announced a cyber war against Slovenia for joining the Czech initiative to purchase ammunition for Ukraine.

Their message on X concluded with the announcement that they would start with the website of the Slovenian president.

Interior Minister Boštjan Poklukar said police were conducting an investigation along with the other relevant authorities and would notify the public of the results once they were available.

"It is true that Russian hackers have claimed responsibility for the attack," he said, but suggested waiting for the the investigation to conclude before jumping to conclusions.

Slovenia cannot expect to be immune to such incidents, Svete said, urging more investment into cybersecurity in the face of escalating cyberwarfare.