It found the RT news channel broke broadcasting rules by failing to preserve due impartiality in seven news and current affairs programmes over a six-week period.
An Ofcom spokesperson said: “Our investigations found that RT failed to maintain due impartiality in seven news and current affairs programmes over a six-week period.
Ofcom may impose a “statutory sanction” on the Russian government-owned broadcaster RT for breaking impartiality rules, while covering the Salisbury attack and wars in Syria and Ukraine.
“Taken together, these breaches represent a serious failure to comply with our broadcasting rules.