The United States and Britain have blamed Russia's Foreign Intelligence Service (SVR), successor to the foreign spying operations of the KGB, for the hack which compromised nine US federal agencies and hundreds of private sector companies.

SVR Director Sergei Naryshkin, a close ally of Kremlin chief Vladimir Putin, told the BBC in Russian that the claims were "like a bad detective novel". 

Asked directly if the SVR was responsible for the SolarWinds attack, Naryshkin quipped with a smile that he would be "flattered" if the SVR had been responsible for such a sophisticated attack but that he could not "claim the creative achievements of others as his own".

Naryshkin said such accusations were absurd and that Russia was not responsible for the cyber-attacks, poisonings, hacks, or meddling in elections that it was blamed for.

The hack of SolarWinds, which was identified in December, gave access to thousands of companies and government offices that used its products. Microsoft President Brad Smith described the attack as “the largest and most sophisticated attack the world has ever seen".