Taxpayers paid close to a million dollars for a campaign that had Sir Rod Stewart record a video version of his 1975 hit Sailing that was played at America's Cup fan zones.

But Tourism New Zealand (TNZ) said the Rock the Dock event, aimed at using the America's Cup as a way to market New Zealand overseas, cost $918,000 but would not say what portion went to the British pop star.

The agency's director of marketing Tony Rogers said the event was part of a campaign to promote New Zealand to key international markets "in preparation for borders reopening in the future".

"To maximise the impact to the New Zealand economy of hosting the America's Cup, businesses and government agencies are running a programme of events and activities to lift New Zealand's profile internationally," Rogers said in response to an Official Information Act request.

"Rock the Dock was part of our leveraging activity that brought New Zealanders together in a show of support for the teams and their fans around the world who are unable to be here."

Rogers said Stewart was chosen because he has global appeal and a strong connection to New Zealand with two of his children born here.

"He's always felt like New Zealand was a second home," he said.

The two children were born during Stewart's 17-year marriage to Auckland model Rachel Hunter.

Rod Stewart's Sailing video was played at America's Cup fan zones. Photo / NZME

However, Rogers would not divulge Stewart's fee for the event, saying it was "commercial in confidence" and releasing it could jeopardise his future contract negotiations.

"The total cost of hosting the event was $918,000. This includes Sir Rod's fees, marketing and promotional budget and production costs associated with the event," he said.

When Sailing was released in 1975, it was not a big hit in New Zealand, reaching just number three in the charts.

But it gained popularity a year later when it was used as a theme for a BBC documentary series, Sailor, about life on the aircraft carrier Ark Royal.

As part of the event, crowds at America's Cup fan zones in 15 centres around the country sang along with a recorded video performance of Sailing with Stewart in London last Saturday.