"As before, neither our American nor our British colleagues have bothered to search for arguments, even weak ones," he said during a regular briefing.
Peskov added that the claims were "groundless" and "unjustified".
Washington and London said in a joint statement Monday that Russia's hacking operation aimed "to support espionage, extract intellectual property, maintain persistent access to victim networks and potentially lay a foundation for future offensive operations".
The US Department of Homeland Security said the hacking was part of a broad operation dubbed Grizzly Steppe, which DHS says comprises concerting cyber attacks by Moscow's civilian and military intelligence agencies.
The announcement came in an unprecedented joint alert that underscored closer cooperation between Western governments fighting what they say is an ongoing, multi-faceted hacking and online disinformation campaign by Moscow.
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