The Labour Party is claiming that John Key directly intervened with the process for a new national convention centre once a SkyCity deal was floated, but the Prime Minister says there's no need to reopen the tender process for the centre.
Labour says it has documents which show that a joint feasibility study for a new convention centre was carried out by the Ministry of Economic Development, Ministry of Tourism and the Auckland City Council in August 2009.
Leader David Shearer said officials recommended developing a further business case and John Key, as Minister of Tourism, was briefed on that.
"At the same time John Key was also made aware of Sky City's plans to expand its own convention facilities. He then called an immediate halt to further work on a business case.
"Three months later, in November 2009, John Key has dinner with casino bosses where he admitted having discussed the centre and 'issues relating to the gambling act' - clearly sealing the deal.
"This raises questions about the extent of John Key's dealings with Sky City," he said.
The Opposition says the negotiation process for a convention centre has been undermined because Mr Key approached SkyCity two years ago and encouraged them to pitch for the convention centre.
Mr Key says that he gave the same treatment to all five bidders for the convention centre, and insists there is no conflict of interest.
SkyCity has offered to pay for a $350 million convention centre in return for gambling concessions.
The deal could allow SkyCity to install up to 500 new pokie machines.
Speaking from Singapore, Mr Key said he encouraged SkyCity to make a pitch for the convention centre in 2010 in his capacity as Minister of Tourism.
Mr Key said he spoke to a number of parties, but no other contenders could match SkyCity's offer.
He rejected accusations the Government was selling legislation, saying it had been a "very transparent process''.
"It's blindingly obvious it won't pay for itself. In the case of SkyCity it's obvious that they would want different paths and different ways of making money, now that's all part of the negotiation that's been upfront from day one.
"They're the only party that's prepared to fully pay for the convention centre.''
It has emerged SkyCity's shareholders were told of close ties to "high-ranking'' Cabinet ministers five days before Mr Key invited the company to bid to build the new centre.
SkyCity chairman Rod McGeoch said the access was enabling the company to change the way it was seen by "key influencers''.
Auckland Mayor Len Brown, who is in China leading a business delegation, issued a statement saying he agreed there was a need for a convention centre in the city to boost the economy and provide more jobs.
"At the same time I am always concerned about the impact of more gambling and if the government proceeds with the proposal I would expect it to include strong measures to mitigate harm.''
The National Party has confirmed it paid in full when it used the SkyCity Convention Centre on election night and other occasions.
Asked whether his party paid for its use of the convention centre for its election night party in November, Mr Key said it was not his job to do party administration.
But the National Party's general manager Greg Hamilton confirmed the party paid to use Sky City on every occasion at commercial rates.