Both S4C and former chair Rhodri Williams are disputing her claims, saying that she was dismissed for gross misconduct, which Ms Griffin-Williams denies.

Documents submitted to the High Court on behalf of the defendants state three TV insiders contacted Mr Williams complaining about Ms Griffin-Williams' alleged behaviour in Nantes.

Those named are Tinopolis executive chair Ron Jones, Carys Owens, wife of the former Wales captain Ken Owens who is managing director of Whisper Cymru and a third, more junior, former S4C employee who the BBC have decided not to name.

In the documents, S4C and Mr Williams allege Ms Griffin-Williams sent messages to Ms Owens using strong language.

Excerpts of the messages quoted in the documents, include Ms Griffin-Williams allegedly telling Ms Owens that "Sian" is fuming with her and using expletives.

It is alleged the messages also show her using expletives demanding Ms Owens gets the "talent here" and in her telling Ms Owens that nobody cares about the crew and: "You just need to bring the talent here. She wants the talent."

Ms Griffin-Williams says the texts quoted are "exaggerated" and that they were "neither bullying nor aggressive".

She is also alleged to have told a senior Whisper producer that the company "would not be having any work [from S4C] for the next 12 months". Ms Griffin-Williams says that is "untrue".

S4C's Gwyn Loader and Nation.Cymru's Martin Shipton are also mentioned in the documents as reporters who have covered the case.

Ms Griffin-Williams has outlined a claim for £565,000 in loss of earnings, undisclosed sums for reputational damage and damage to her health and feelings.

S4C said it would be inappropriate to comment on ongoing proceedings. Mr Williams said he had nothing to add to his defence documentation.

Expletive messages shown in S4C court case documents