ACT MP David Garrett is denying allegations of inappropriate behaviour levelled at him by the Labour Party.
Labour claims Mr Garrett challenged Labour MP Clayton Cosgrove at a closed session of the law and order select committee on Wednesday to "take this outside" following an exchange between the two men.
Labour MP Carmel Sepuloni has written to Parliament's Speaker Lockwood Smith alleging Mr Garrett breached Parliamentary privilege.
Ms Sepuloni says she laid the complaint because there was behaviour she deemed inappropriate.
Mr Garrett has not returned calls from Radio New Zealand.
But in a letter to Dr Smith, which has been given to media, Mr Garrett categorically denies inviting Mr Cosgrove to "take this outside", or making any invitation to settle the disagreement violently.
ACT leader Rodney Hide says there was no threat or breach of privilege by his MP and he is calling on Labour to apologise to Parliament and Mr Garrett.
Mr Hide says the implication of the exchange was 'let's leave it outside or let's actually sit down and do the work rather than play games'.
The Speaker must now decide whether to refer the matter to Parliament's privileges committee.