He replied: "I attended a dinner with the Sky City board 4 November 2009 where we discussed a possible national convention centre and they raised issues relating to the Gambling Act 2003".
Mr Key said he was unable to speak for other ministers as to whether they had met casino representatives.
Mr Key's spokesman today refused to say what date Mr Key's offer to make a deal with Sky City was made.
Labour leader David Shearer said he was appalled.
"The fact that John Key approached SkyCity to say, 'look, if you do this for us we'll allow you to have more pokie machines, and don't worry I'll pass a law through parliament allowing you to have more pokie machines." That frankly is shonky, and it smells," Mr Shearer told Newstalk ZB.
"What he's done with this deal is increase the amount of pokie machines and gambling and therefore the social harm to Auckland. I just think that's a price that we're not prepared to pay."
Mr Shearer said Mr Key was effectively selling the law that controlled pokies.
The Government is still negotiating the deal for the $350 million convention centre in downtown Auckland which Mr Key has said will create 900 jobs during the construction phase and 900 jobs when it begins operating.
However, with reports that the Government may amend the Gaming Act to allow SkyCity to operate up to 500 more gaming machines, the Problem Gambling Foundation fears the expansion will drive an upsurge in gambling addiction.
Mr Key has dismissing reports of up to 500 more machines as speculation but refused to indicate what the number may be other than to say it was "a small adjustment up".
Mr Key has previously said the Auckland Council's "sinking lid" policy on gaming machines in pubs and clubs means fewer gaming machines overall.
Meanwhile, should the deal reach fruition, any changes to the Gambling Act that would be required would not be conscience vote for National MPs.
That was because Mr Key regarded the issue as primarily an economic one.
"It's largely the issue of a piece of infrastructure for tourism and it's an important part of building that tourism model."