One of the UK’s former top civil servants has said that the UK has targeted Russian leaders in response to aggressive behaviour from Moscow.

Sir Mark Sedwill, the former cabinet secretary, told Times Radio that the UK’s approach has been successful.

“Russia is operating in what the aficionados call grey space, that gap between normal state relations and armed conflict, with cyber-attacks, information warfare and disruption campaigns,” he said.

“It is important that we are capable of manoeuvring in the grey space and doing so effectively. We can’t leave the initiative to our adversaries.

“There are vulnerabilities that we can exploit too. We just don’t always talk about them.”

Interestingly, given the fact that the UK has for many years turned a blind eye to a huge inflow of Russian money, he said the influx of illicit money had also been targeted.

Sedwill was also the national security adviser until he left he post in September. He said that other covert measures have been taken against high-level Russian interests but added that he could not disclose the details.