The UK, US and EU have publicly blamed Russia for a cyberattack on communications company Viasat an hour before Vladimir Putin’s invasion of Ukraine.

The attack was aimed at the Ukrainian military but hit civilian internet users in Ukraine and central Europe.

Intelligence from the UK and US indicated Moscow was behind a series of cyber incidents in the run-up to the invasion.

The UK’s National Cyber Security Centre (NCSC) has assessed that Russian military intelligence was almost certainly involved in the January 13 attacks on Ukrainian government websites and the deployment of Whispergate destructive malware.

The NCSC also assesses it is almost certain Russia was responsible for the subsequent cyberattack affecting Viasat on February 24 as Moscow’s forces prepared to invade.

Foreign Secretary Liz Truss said: “This is clear and shocking evidence of a deliberate and malicious attack by Russia against Ukraine which had significant consequences on ordinary people and businesses in Ukraine and across Europe.

“We will continue to call out Russia’s malign behaviour and unprovoked aggression across land, sea and cyberspace, and ensure it faces severe consequences.”

The attack on Viasat, while primarily aimed at Ukraine’s forces, had a knock-on effect on personal and commercial internet users, and even wind farms in central Europe.

The decision to publicly blame Russia for the attacks came as cybersecurity leaders from the Five Eyes intelligence alliance – the UK, US, Canada, Australia and New Zealand – the EU and other allies met at an NCSC conference in Newport, South Wales.

Meanwhile Prime Minister Boris Johnson is to visit Sweden and Finland on Wednesday as they consider whether to apply for Nato membership in the wake of Russia’s invasion of Ukraine.

Downing Street rejected suggestions he was seeking to pressurise them into joining the western military alliance as “disinformation”.

“It is about not just Ukraine but the security of Europe more broadly,” the Prime Minister’s official spokesman said.

“We understand the positions of Sweden and Finland and that is why the Prime Minister is going to discuss these broader security issues.”

Support for joining Nato has risen sharply in both countries since Russia invaded Ukraine, despite their previous tradition of neutrality.

In her Mansion House speech last month, Ms Truss said that if they did apply for membership, they should be admitted “as soon as possible”.