The freeze to RT's bank accounts does not appear to come into effect until December 12 although the broadcaster said it had received no explanation as to why Natwest is preparing to sever its ties.
RT has come under fire from critics who argue the broadcaster is a means of propaganda and partisan reporting with British broadcasting watchdog Ofcom ruling against the media outlet in the past.
In the wake of Natwest closing the U.K. accounts of RT's employees, Margarita Simonyan, editor-in-chief, adopted a somewhat sarcastic tone on Twitter by stating, "Long live freedom of speech!".
Sarah Hinton-Smith, head of the commercial and private media desk for the Royal Bank of Scotland Group, of which Natwest is a part, said the decision had "not been taken lightly".
Adding, "We are reviewing the situation and are contacting the customer to discuss this further. The bank accounts remain open and are still operative."
In a statement prepared on Tuesday by the Russian embassy, it expressed "deep concern" on learning that Natwest intends to close the banking services of RT. It went onto add: "This openly political decision follows many similar acts of harassment and intimidation against Russian news outlets in the U.K."