The West has accused Moscow of being behind a string of sabotage attacks on European soil aimed at deterring Ukraine's backers from sending support to Kyiv.

"Allies are working very hard to make sure when it comes to sabotage, cyber-attacks, energy blackmail, that we take all the measures necessary to counter that," Rutte said after talks with NATO foreign ministers.

"These include enhanced intelligence exchange, more exercises, better protection of critical infrastructure, improved cyber defence, and tougher action against Russia's shadow fleet of oil exporting ships."

NATO officials said the alliance was working on a new strategy to combat Russian and Chinese hostile actions for a summit next June in The Hague.

The alleged hybrid campaign poses a problem for NATO as it exists in a grey zone often seen as beneath the level of threat that could trigger the alliance's mutual defence clause.

"This year, there were 500 suspicious incidents in Europe. Up to 100 them can be attributed to Russia, hybrid attacks, espionage, influence operations," said Czech Foreign Minister Jan Lipavsky.

"We need to send a strong signal to Moscow that this won't be tolerated."

German Foreign Minister Annalena Baerbock said Russian President Vladimir Putin was "waging this hybrid war of aggression with hybrid attacks on our European peace order.

"He is trying to shake our democratic societies," she told journalists.

Worries about sabotage were recently heightened after undersea cables in the Baltic sea were cut, with suspicion falling on a Chinese vessel.

"We will continue to expand our monitoring of hybrid attacks and draw the appropriate political conclusions from this, as well as the de facto expansion of monitoring in the Baltic Sea region," Baerbock said.