London: Theresa May has accused Russia of meddling in elections and planting fake stories in the media in an extraordinary attack on its attempts to "weaponise information" in order to sow discord in the west.
The prime minister spoke out against "the scale and nature" of Russia's actions during an address at the lord mayor's banquet, saying it was "threatening the international order on which we all depend".
Listing Russia's attempts to undermine western institutions in recent years, she said: "I have a very simple message for Russia. We know what you are doing. And you will not succeed. Because you underestimate the resilience of our democracies, the enduring attraction of free and open societies, and the commitment of western nations to the alliances that bind us.
"The UK will do what is necessary to protect ourselves, and work with our allies to do likewise."
Her speech is a serious escalation of the UK's warnings about Russia as Boris Johnson, the foreign secretary, prepares to visit Moscow before the end of the year as part of a strategy of cautious engagement with Vladimir Putin's administration.
Since Russia's annexation of Crimea from Ukraine, May said Russia had "fomented conflict in the Donbass [eastern Ukraine], repeatedly violated the national airspace of several European countries, and mounted a sustained campaign of cyber-espionage and disruption".
"This has included meddling in elections, and hacking the Danish ministry of defence and the Bundestag [German parliament], among many others," she told the audience of City of London business figures.
"It is seeking to weaponise information. Deploying its state-run media organisations to plant fake stories and photo-shopped images in an attempt to sow discord in the west and undermine our institutions."
She said the UK did not want to "return to the Cold War, or to be in a state of perpetual confrontation" but the UK would have to act to protect the interests of the UK, Europe and rest of the world if Russia continues on its current path. A Downing Street source said May was not making the intervention in response to any specific event but rather to a growing body of evidence that Russian agencies have been attempting to interfere with western politics.
The prime minister's strong criticism of Russia's activities comes in contrast to comments this weekend by Donald Trump, who said on Saturday that he believed Vladimir Putin's denials of having meddled in the American presidential elections.
Asked by reporters if he had raised the issue of Russian interference during conversations with Putin at a summit in Vietnam during a tour of Asia, Trump said: "Every time he sees me, he says, 'I didn't do that.' And I believe – I really believe that when he tells me that, he means it."
The U S president appeared to contradict that stance on Sunday when he said he was "with our agencies" on the issue.
May did not say on Monday whether she was concerned with Russian intervention in any UK democratic processes, but Ben Bradshaw, a leading Labour MP, is among those to have called for a judge-led inquiry into the possibility that Moscow tried to influence the result of the Brexit referendum.
Russia has been accused of running "troll factories" that disseminate fake news and divisive posts on social media. It emerged on Monday that a Russian bot account was one of those that shared a viral image that claimed a Muslim woman ignored victims of the Westminster terror attack as she walked across the bridge.
The account that tweeted the picture, @SouthLoneStar, was identified as a Russian bot as part of a US investigation into the country's influence on the 2016 presidential election.
The prime minister's attack on Russia's actions also come as MPs on the House of Commons media committee prepare to begin an inquiry into whether Moscow has tried to interfere in British politics, which is due to hear from representatives of both Twitter and Facebook.
May told the banquet that she would do everything possible to protect Europe's security cooperation even though the UK is leaving the EU and argued that reform of Nato would maintain a vital alliance in deterring and countering hostile Russian activity.