An American anchor on Russian state television has delivered an emotional rebuke of Moscow's intervention in Ukraine and criticised the media's biased news coverage.

Russia Today responded by saying it was sending Abby Martin to Crimea so she could learn more about the situation.

Martin, a Washington-based journalist with the English-language channel, wrapped up her show on Tuesday by saying "what Russia did is wrong" and that military intervention was never the answer.

"I can't say enough how strongly I am against any state intervention in a sovereign nation's affairs," she said at the end of the show, Breaking the Set.

"What Russia did is wrong," she said. "Military intervention is never the answer, and I will not sit here and apologise or defend military aggression.

"Furthermore, the coverage I have seen of Ukraine has been truly disappointing from all sides of the media spectrum and rife with disinformation," Martin said, before saying goodbye and marching off the set.

Russia Today's coverage of the Ukrainian crisis has followed the Kremlin's line, devoting broadcasts to "hammer-wielding nationalists" in Kiev and calling the soldiers occupying Crimea "self-defence forces" despite evidence they are Russian troops.

Martin's colleagues in Russia were apparently caught off-guard by her comments. One, Darya Pushkova, tweeted that she should do her show "out of what she calls are occupied territories and see for herself".

"That's exactly right," the RT editor-in-chief, Margarita Simonyan, wrote in response.

Russia Today later released an official statement. "Contrary to the popular opinion, RT doesn't beat its journalists into submission, and they are free to express their own opinions, not just in private but on the air. This is the case with Abby's commentary on the Ukraine," it said.

"We respect her views, and the views of all our journalists, presenters and programme hosts, and there will be absolutely no reprimands made against Ms Martin.

"In her comment Ms Martin also noted that she does not possess a deep knowledge of reality of the situation in Crimea. As such we'll be sending her to Crimea to give her an opportunity to make up her own mind from the epicentre of the story."

Martin, responding on Twitter to coverage of her remarks and messages of support, said: "I am not going to Crimea despite the statement RT has made."