Sacked AA executive chairman Bob Mackenzie has filed a claim alleging wrongful dismissal with the High Court.
In court papers seen by The Times Mackenzie accuses the AA of having little regard for his mental wellbeing.
He was sacked for "gross misconduct" in August last year after he punched AA head of insurance Mike Lloyd during a work event held at the Pennyhill Park hotel in Bagshot, Surrey.
The former boss does not deny the assault, but claims he was suffering from stress as a result of work pressures.
Mackenzie alleges the incident was used as a pretext to oust him and gain control of shares, which he claims could be worth between £85m and £220m if company performance conditions are met.
A clinical psychologist has contributed to the claim in a report which says Mackenzie had been suffering symptoms for several months as "a toxic combination of extremely high stress levels over the last few years", The Times reports.
The AA responded to last night's reports saying: "We received particulars of claim from Robert Mackenzie at the High Court of Justice Chancery Division at 3.58pm today. We were astonished to receive the claim after the documentation was leaked by or on behalf of Mr Mackenzie to the press earlier in the day, in a clear breach of confidentiality.
"The board and all the directors acted with utmost propriety and appropriately in respect of the matters of this claim. Mr Mackenzie was dismissed on August 1, 2017 having launched an unprovoked, sustained and violent attack on a colleague. We will vigorously contest the claim."
In his role as executive chairman of the AA, Mackenzie oversaw all elements of the business, including hotel services. He regularly appeared at the annual AA Hospitality Awards to present the key accolades.
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