Boris Johnson claims there is "plenty of evidence" that Russia is able to hack UK politics - following similar warnings from GCHQ.
Ahead of a meeting with his Russian counterpart, the Foreign Secretary said there was no doubt Moscow had been up to "all sorts of dirty tricks" in relation to political interference.
Mr Johnson accused Moscow of bringing down French TV stations, hacking the US Democratic National Convention, and even suggested it might have engineered an attempted assassination of Montenegro's Prime Minister.
The former London Mayor's comments come in the wake of a Sunday Times report that GCQH has written to Britain's major political parties with advice how to withstand potential Russian hackers.
Speaking to Peston on Sunday, Mr Johnson said: "We have no evidence the Russians are actually involved in trying to undermine our democratic processes at the moment.
"But what we do have is plenty of evidence that the Russians are capable of doing that."
The Foreign Secretary is due to visit Russia soon to meet with Moscow's foreign minister Sergey Lavrov.
Asked what his message to the Kremlin would be, Mr Johnson said:" My personal feeling is one of deep, deep sadness".
He said that UK-Russia relations were in "quite a good phases" a decade ago, but that times had changed.
Speaking of alleged Russian interference in global politics, Mr Johnson said: "There is no doubt that they have been up to all sorts of dirty tricks.
"There is very little doubt that the Russians are behind these things, to say nothing of what they've done in Ukraine."
Asked what the UK's approach to Russia should be, he answered: "What we need to have is a twin-track approach.
"As the Prime Minister has said, we've got to engage but we have to beware."