Mr Mitchell, a former policeman, said he had many years of working with intimidatory people and did not immediately recognise the seriousness of the situation.
"But sitting in the vehicle with my wife it was obvious she was shaken and the nature of the threats had shaken her.
"I've now had time to reflect on the abusive behaviour of Mr Dotcom at the function I attended last year. The violence of the threats towards the Prime Minister have not left me and today I felt it was important to place these matters on the record in this House.
"I believe the people of this country are beginning to question the true motives of Mr Dotcom. From my own experience he is a man who uses threats and intimidation of people to get what he wants."
He said he did not originally believe the claim that other MPs were working with Mr Dotcom until it became clear several Opposition MPs had been there.
He went on to attack those Opposition MPs who had visited Dotcom, asking if it was true Dotcom had tasked Labour with developing the IT policy he had been working on or if Green co-leader Russel Norman had promised to help with his extradition bid.
Labour MP Trevor Mallard objected at the end, saying it was out of order for Mr Mitchell to claim other MPs were working under the instruction of Mr Dotcom.
Kim Dotcom responded to Mr Mitchell's claims on Twitter: "The only threat I ever made to those who abuse their power and think they are above the law: "The truth will come out''.''
