Britain on Monday said it refused to accredit the Russian state media outlets “because of their active role in spreading disinformation.”
Some 60 ministers and 1,000 journalists and members of civil society are expected to attend the meeting on Wednesday and Thursday co-hosted with Canada. He mocked what he called “the absurdity of what is happening.”
“We can only regret this,” he added.
The Russian Embassy in London previously condemned the decision relating to RT as “direct politically-motivated discrimination” and said it had complained to the Foreign Office.
RT said in a statement that “it takes a particular brand of hypocrisy to advocate for freedom of press while banning inconvenient voices and slandering alternative media.”
In December last year, British media regulator Ofcom found RT had broken impartiality rules in several programs broadcast after the nerve agent attack in the city of Salisbury.
Moscow has denied claims by London that it approved the attack on former Russian double agent Sergei Skripal and his daughter in March last year.
Organizers of the London conference say it is intended to increase international discussion and cooperation on the issue of media freedom, including fake news.
A spokesman for Britain’s Foreign Office said journalists from other Russian news organizations will attend the conference.