US President Donald Trump's "fake news" attacks on the media are undermining democracy and drowning out genuine reporting, David Cameron has said.
Mr Cameron, who was UK prime minister until 2016, said Mr Trump's criticism of CNN and the BBC was "not just a questionable political tactic - it's actually dangerous".
He also accused Russia of spreading anti-western propaganda.
Mr Cameron made the claims at an anti-corruption conference in London.
He said "misappropriation" of the term "fake news" deflected attention away from real abuses of democracy.
Describing how "real democracy" is the "biggest weapon" against corruption, he argued that without rigorous journalism "fake news" is better able to get a foothold.
"When Donald Trump uses the term 'fake news' to describe CNN and the BBC, that is not just a questionable political tactic - it's actually dangerous," he said.
"Let me put it like this, President Trump: fake news is not broadcasters criticising you, it's Russian bots and trolls targeting your democracy - pumping out untrue stories day after day, night after night.
"When you misappropriate the term fake news, you are deflecting attention from real abuses.
"Ignoring what's happening on social media is facilitating a form of corruption that is undermining democracy," he said.
Mr Cameron also used his wide-ranging lecture at the conference organised by anti-corruption agency Transparency International, to turn his fire on Russia.
He argued that it is "almost always autocratic, illiberal, anti-democratic states" that use "corruption as a weapon of foreign policy" to "interfere in other countries' affairs, buying influence through gift-giving and donations for political campaigns".
He said the EU had not acted decisively enough to combat Russian subversion of its democracies.
"To be honest, this is one area where, far from being too quick to act, the EU has been far too slow," he said.
"Barack Obama used to challenge European leaders over how we seemed to ignore or even tolerate Russian subversion of some eastern European business, energy, media, or even political interests. He was bang on target."
Mr Cameron also used his speech to defend the importance of traditional journalism, claiming reporters are "often the only ones on the scene when it comes to corrupt acts", yet the absence of them at inquests, in court and council meetings means "so much goes unchecked and unquestioned".
"In its stead - thanks to the growth of technology and the increasing domination of social media - propaganda, misinformation and 'fake news' are better able to get a foothold," he said.
"There's the danger that will then squeeze out the genuine scrutineers and drown out the genuine reporting - some of it at the behest of those foreign governments I've just talked about."