Ukraine’s state security service claims Russia is preparing a large-scale cyber attack ahead of the Champions League football final, due to be held in Kyiv on Saturday.
The allegation comes after a major cyber security firm warned that hackers have infected 500,000 routers in dozens of countries.
The malware is said to have been used in previous attacks that the US has attributed to Moscow.
CISCO Researcher Craig Williams explained: "From a global standpoint we saw this malware pretty much distributed evenly across the planet. All of that changed about two weeks ago when we saw a new command and control server pop up and that command and control server specifically targeted Ukraine."
It's not known what the hackers have planned but the malware gives them remote access to infected machines.
The Kremlin has not commented but has previously denied accusations that it is behind a global hacking programme that has included interfering in the US 2016 presidential election .