A "disturbing pattern" of alleged Russian interference with European elections has emerged, warned Defence Secretary Sir Michael Fallon, adding that Nato leaders recently discussed measures to counter Russia's "hybrid warfare" campaign.

"We have seen a rather disturbing pattern of these allegations now of direct Russian interference in countries as far apart as Bulgaria, the referendum in the Netherlands, continuing pressure on the Baltic States," Sir Michael told MPs during defence questions yesterday (12 December).

Sir Michael also accused Russia of a "huge" rise in submarine activity off the British coast, and of a renewal of aggressive naval exercises.

Earlier in the year, the Netherlands voted in a referendum to block EU funds being directed to Ukraine, where government forces are battling Kremlin-sponsored militias. The far-right Freedom Party of Geert Wilders, who has praised Russian President Vladimir Putin, currently leads in polls ahead of March's parliamentary elections.

In Bulgaria, pro-Russian Rumen Radev recently won the presidential election.

MI6's new chief, Sir Alex Younger, warned last week of the threat of Russian "hybrid warfare" to democracies, involving the use of propaganda, hacking attacks and sponsoring extremist parties to subvert electoral processes.

Sir Michael said that at a recent Nato summit in Warsaw, leaders discussed countermeasures.

"We agreed at Warsaw that the European Union and Nato would come together to cooperate on hybrid warfare, in particular, and to look at the various techniques that were necessary to help us all resist that kind of pressure," he said.