Pro-Russian hackers have attacked the websites of several Italian institution, including the defence ministry and the senate, ANSA news agency reported on Wednesday.
The hacker group "Killnet" claimed the attack, ANSA said, which also involved the National Health Institute (ISS) and the Automobile Club d'Italia, a national drivers' association.
The websites were offline at 7.00 p.m. (1700 GMT). The defence ministry website displayed a message saying it was under maintenance.
Police said an investigation was ongoing, but made no further comment. The defence ministry and the Italian cyber security agency did not immediately respond to a request for comment.
After Russia's invasion of Ukraine, many western governments have raised the level of alert over possible cyber attacks on IT systems and infrastructure.
Late in March, Italian railway company Ferrovie dello Stato Italiane (FS) temporarily halted some ticket sale services fearing it had been targeted by a cyber attack.
In April, the ecology transition ministry said it had to shut down all its IT systems due to external threats.
(Reporting by Angelo Amante; Editing by Alex Richardson)