Mr Key's active involvement in the appointment of childhood acquaintance Ian Fletcher as the GCSB chief was well established last year by Labour MP Grant Robertson, including a breakfast meeting between the pair in June 2011 at the Stamford Plaza.
TV3 identified another meeting between Mr Key and Mr Fletcher, on December 12, 2011, the week surveillance of Kim Dotcom began.
Mr Fletcher was appointed in September. He did not take up the post until January 30, 2012 but was visiting New Zealand in December.
Mr Key said acting GCSB chief at the time, Simon Murdoch, brought Mr Fletcher over to see him in his Beehive office on December 12.
"I can't tell you exactly everything we talked about because I would never say that," Mr Key said "but I can tell what we didn't talk about.
"We didn't talk about Kim Dotcom because it is impossible to talk about someone you don't know."
Mr Dotcom tweeted this after that that was "the logic of a liar."
Kim Dotcom insists he has proof that Mr Key is lying when he says he first heard about him on January 19, the day before his Coatesville mansion was raided by the FBI and that the proof will force Mr Key to resign.
Mr Dotcom is facing extradition proceedings by the United Sates where he is wanted on copyright, racketeering, money laundering and wire fraud charges.
He has been giving evidence at the trial of Act MP John Banks who is charged with filing a false electoral return in 2010 by knowingly recording donations by Mr Dotcom and Sky City as anonymous.
Mr Dotcom claimed in court Mr Key had heard about him because Mr Banks told him he had told the Prime Minister about a New Year's fireworks display being put on by Mr Dotcom.
Mr Key said he had "no idea what John Banks said to Kim Dotcom but all I know is he has never spoken to me about going to fireworks."
He would never go to such fireworks anyway because he always spent Christmas and New Year in Hawaii.