The watchdog announced in December that current affairs shows on the channel, including one hosted by former MP George Galloway, broke its impartiality rules over a six-week period in 2018.
Subsequent reporting from Russian media and the UK’s Bellingcat website identified two men with links to Russian intelligence agencies who were in Salisbury at the time of the attempted assassination.
Ofcom is now considering how to sanction the channel. Punishments could range from a requirement to make corrections on air, to the full revocation of RT’s broadcast licence.
In a statement released on Thursday, a spokesperson said: “We firmly believe that none were in breach. RT is left with no choice other than to seek Judicial Review of the matter.”
When defending against the charges of impartiality, RT has said it should not be seen as impartial because its viewers know it is “avowedly Russian”.
Critics of the network say it repeatedly takes a pro-Russian and anti-western viewpoint and that conspiracy theorists are frequently invited on to air views which seek to sow doubt and confusion about western governments and institutions.
In the aftermath of the Skripal poisoning, RT and numerous other Kremlin-backed media channels were responsible between them for broadcasting tens of different explanations for who could have been responsible, other than the main suspect, Russia.
RT has argued these alternative viewpoints, no matter how far from factual they may be, are crucial for “informed debate”.
Today’s statement said: ”Ofcom required that RT devote yet more of its time to presenting the same mainstream viewpoints of other broadcasters, instead of delivering the alternative perspectives our viewers have come to rely on.
“These alternative viewpoints are essential to a well-informed public debate.
“We are now placing the matter in the hands of the courts.”
The ongoing row sparked the Russian Ambassador to say last month that if RT is closed in the UK, his government will take similar measures against the BBC in Russia.