Claims from a special adviser that former DUP minister Jonathan Bell tried to break his finger during a heated row in London have been published by the RHI inquiry.
The dysfunctional relationship between Mr Bell and his adviser Timothy Cairns has already been revealed during the inquiry, which is looking into how costs of the green energy scheme spiralled out of control.
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However, the inquiry has now published Mr Cairns witness statements ahead of his appearance before the panel on Tuesday.
Mr Cairns was special adviser to Mr Bell during his time as Minister at the Department for Enterprise, Trade and Investment (DETI) at the height of the RHI crisis.
Asked by the inquiry to describe his relationship with Mr Bell, Mr Cairns said: "Jonathan exhibits a changeable personality. Jonathan usually presented a confident manner. During these periods our relationship was good.
"At other times Jonathan would be emotional, quoting the bible and wondering about the eternal destiny of his soul. Again, during these periods our relationship was good. Jonathan also exhibited an explosive personality, particularly when he was told that something he wanted may not/would not be possible."
During a breakfast meeting meeting in London on June 10 2015 a row broke out with between Mr Bell and Mr Cairns. The pair were in London to meet then Secretary of State for Energy and Climate Change Amber Rudd.
Mr Cairns, in his written evidence, said Mr Bell became "enraged" after a disagreement about the Northern Ireland Renewables Obligation (NIRO).
He said he had advised the minister to seek advice from other senior figures in the DUP.
Mr Cairns said: "Mr Bell became enraged. I knew from previous experience that I should retreat from the situation.
"I had not checked out of my room, therefore to try and defuse the tension I stood up and said I was going to check out and we could resume discussions in a few minutes. Mr Bell ordered me to sit down, but I went to my room and collected my bags and checked out."
Upon returning Mr Cairns was told by a colleague that Mr Bell was refusing to leave the breakfast table until he returned.
"I therefore went back to the table were Jonathan started behaving in an aggressive manner."
Mr Cairns added: "By this stage neighbouring tables were looking round.
"For my part, I certainly did not handle the conflict well. I was embarrassed and simply wanted the incident to end. I said 'well Jonathan if you want to be the man with big balls and just make the decision go right ahead, but this is an East Belfast matter and if I was you I would consult Peter Robinson at the very least'."
Mr Cairns claimed Mr Bell was "enraged" by what he saw as "disrespect."
He said: "While I was making this comment I must have been wagging my finger, Jonathan reached to grab my finger, I pulled it back from his grip.
"In an aggressive tone Jonathan said 'if you wag your finger at me again I will break it'."
Mr Cairns said he felt under "immediate physical threat".
Mr Bell then allegedly told his special adviser that if he didn't apologise he would fire him.
Mr Cairns said: "I replied that if that’s how he felt he should fire me. He proceed to point out his finger and say 'you’re fired'. I was relieved to be getting away from the table and an obviously enraged and aggressive person who had threatened me physically."
During his evidence last week, Mr Bell strongly denied Mr Cairns allegations of any physical violence and bullying.