A Russia Today reporter based in London has resigned with immediate effect in protest at the station’s coverage of yesterday’s plane crash in Ukraine.

Sara Firth had worked at Russia Today for five years, joining the Russian government-funded station in Moscow straight after doing an MA in journalism at City University in London. She has since been posted in London.

Firth described the Malaysia Airlines flight crash coverage as “the straw that broke the camel’s back for me” and handed in her resignation this morning.

Russia Today has been criticised for suggesting the crash is the fault of Ukraine. Most other media outlets have suggested a more likely explanation is that pro-Russian separatists were responsible for shooting down the passenger jet. So far it is estimated that around 300 people died in the crash.

“Yesterday when the story broke you get the kick in your stomach when you’re going to get the facts and it’s this huge story,” she told Press Gazette.

“And I walked into the newsroom and they were running an eye-witness account of God-knows who the person was blaming the Ukrainian government, and it is such a volatile situation.”

Firth, who told Press Gazette in an interview in 2012 that facts are her “religion”, said: “I said it then, if I was asked to burn the facts and not tell the truth I’d be a goner, and so I’m gone…

“And it’s the level of disrespect for the facts that really bugs me.

“And so I made my decision yesterday when we started covering the story and this morning woke up and I just knew that I can’t go back in any more.”

She added: “The thing is once I made the decision, you have to be honest with yourself and it’s so difficult…. Once you start telling the truth it’s brutal.”

In response to her resignation, a Russia Today spokesperson said that the channel and Firth "apparently… have different definitions of truth".

Firth told Press Gazette: “They believe that fully, 'definitions of the truth'. There you go – that’s RT. What can you say?”

Firth said that "rule one of the Russia Today style guide is to blame Ukraine, or anything else, rather than Russia". “It’s scary that it’s genuine RT guidance on how to do a story, and you have to believe it to succeed there.You stop believing that what they say is the way it is and you stop being useful to them…

“It’s not a nice organisation either.”

A Russia Today spokesperson said: "We were not surprised by Sara Firth’s decision to leave RT after 5 years as a Moscow and London correspondent, as she has recently informed us that she was likely to take an offer from another firm.

"The plane crash is an absolutely terrible tragedy, there are a lot of questions that surround it and everybody is looking for answers. More than 15 RT journalists are working on this story – from Moscow, from the Russian-Ukrainian border, London, Berlin, Washington. RT Spanish journalist Francisco Guaita was one of the first TV correspondents to get to the scene late last night; our reporters are in Netherlands and in Malaysia.

"Sara has declared that she chooses the truth; apparently we have different definitions of truth. We believe that truth is what our reporters see on the ground, with their own eyes, and not what’s printed in the morning London newspaper. In our coverage, RT, unlike the rest of the media, did not draw conclusions before the official investigation has even begun. We show all sides of the story, even if everyone else has already decided which side is to blame."