It emerged last week that Mr Key's personal lawyer, Ken Whitney, had lobbied the Governmentin 2014 because of concerns the foreign trusts regime was about to change.
In a letter to then-Revenue Minister Todd McClay in December 2014, Mr Whitney said the Prime Minister had told him the Government had no plans to tighten the rules for the industry. Speaking to Radio New Zealand, Mr Key was asked if Mr Whitney misrepresented his position to the Minister.
"Correct. Because I wasn't aware of any changes."
Asked if he was disappointed, Mr Key replied that "sadly" people often dropped his name in conversations.
"People who barely know me, who don't often talk to me, often drop my name in things.
"In Ken Whitney's case I know him extremely well. He's been my long-standing lawyer ... But that is the limit of the exchange that we had."
Mr Key said that he had told his lawyer that he was not aware of any changes being planned by the Inland Revenue Department, and referred him to the minister for further discussion.