Several French state bodies have been hit with cyberattacks of "unprecedented intensity", Prime Minister Gabriel Attal's office said Monday, while insisting the government had been able to contain the impact.

"Many ministerial services were targeted" from Sunday "using familiar technical means but of unprecedented intensity," Attal's office said, without providing further details of the targets.

A security source told AFP that the attacks "are not currently attributable to Russia," an obvious suspect for many given Paris' support for Kyiv since the invasion of Ukraine.

The PM's staff added that a "crisis cell has been activated to deploy countermeasures", meaning "the impact of these attacks has been reduced for most services and access to state websites restored."

Specialist services including information security agency ANSSI were "implementing filtering measures until the attacks are over".

The latest cyberattack to hit France follows a warning from Attal's defence adviser last week that the Paris Olympics and European Parliament elections this summer could be "significant targets".

Meanwhile, Defence Minister Sebastien Lecornu said last month that protection against "sabotage and cyberattack" by Russia should be stepped up, in an internal note seen by AFP that said his ministry was top of Moscow's target list.