A ceremony greets Singapore Airlines' inaugural flight from Singapore and Canberra to Wellington on September 21.

A decision to subsidise Singapore Airlines new Wellington flights for the next decade saw virtually nothing put in writing.

Documents released by the Wellington City Council show that apart from a presentation made to councillors after the decision was made, the council generated a single two page document, which refers to the subsidy only in passing.

In January it was revealed that Wellington City Council chief executive Kevin Lavery had approved a subsidy for a new Singapore-Canberra-Wellington route from the Destination Wellington fund. The route launched on September 21.

Ross Giblin/FAIRFAX NZ Wellington City Council chief executive approved a subsidy to bring Singapore Airlines to the capital which could be worth $8 million over a decade.

The council has never disclosed the maximum Singapore Airlines, one of Asia's largest airlines, could be paid, but documents suggest it could be $800,000 a year for 10 years.

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The Ombudsman, the authority appointed to monitor the official information disclosures of government agencies, has investigated the council on the information it released, and concluded that no other written documents exist.

The release suggests Lavery neither sent nor received a single piece of correspondence on the request, commissioned no analysis on Wellington Airport and Singapore Airlines' claims about the route, or had any written contact with Singapore Airlines on the payment whatsoever.

On Monday Lavery and the council refused to comment on the subsidy or the decision making process behind it.

Justin Lester, who as deputy mayor was involved in the negotiations to bring Singapore Airlines to Wellington, defended the process, saying the spending was within Lavery's authority.

"We gave them a pool of money to determine how it's best spent in marketing Wellington," Lester said, adding that he would be "highly surprised" if there was nothing else in writing.

Lester said Lavery's approach to digital communication may be behind the lack of correspondence.

"He doesn't send emails."

Lavery has written about the subsidy at least once, sending a furious email to councillors after some details of it were obtained by the media back in January.

"This undermines our relationship with Singapore Airlines. It also potentially compromises the interests of our own ratepayers."

Steve Sanderson, chief executive of Wellington Airport, said the airport and Singapore Airlines had jointly supplied the information for Lavery to make a "good call".

The joint application was six pages long, with little over a page related to the money the airline and airport were seeking from council.

"There was no shortcut taken, and we followed due process," Sanderson said.

Air New Zealand flights to Rarotonga received government funding and "most councils" also supported flights, Sanderson said.

Asked if he had been probed by the council about whether Singapore Airlines would have flown here without the payment, Sanderson said he was not close enough to the scrutiny of the business case to answer.

"It was not put to me."