About 10,000 people are believed to be missing out on a New Year’s Eve party in Sydney as it has been postponed just hours before it was due to start.

Tickets for the event at the newly-opened Wet `n’ Wild theme park cost between $110 and $200 and it will now take place on Australia Day.

NSW Fair Trading says it expects the event promoter to provide a refund to people who cannot attend the postponed event in January.

According to a statement on the Wet `n’ Wild website, One Cube Entertainment, a promotions company organising the event, made the decision to postpone the NYE Festival due to a major technical production issue.

“We sincerely apologise for any inconvenience caused and are currently working on something even better for Australia Day,” a One Cube Entertainment spokesperson said in the statement.

An artist manager told AAP One Cube Entertainment had attributed the cancellation to Wet `n’ Wild expressing occupational health and safety concerns.

The manager, who spoke on the basis of anonymity, said contractually his artist was still entitled to a full fee.

NSW Fair Trading Commissioner Rod Stowe said under Australian consumer law, a remedy was available if a consumer did not get the service they paid a supplier for.

“You can seek to have refund provided,” he told AAP.

Mr Stowe said some ticket holders could not or did not want to attend the postponed event on Australia Day.

“We are expecting the promoters will provide refunds to the consumers who cannot attend,” he said.”

People who paid for tickets on credit cards will be able to apply for a charge back from their credit institution, Mr Stowe added.

A father called Mick told Macquarie Radio his daughters had been trying to contact Wet `n’ Wild since finding out about the event postponement on Facebook.

“We have been trying to contact Wet `n’ Wild this morning and get a number for this promoter because obviously the kids want a refund but no luck so far,” he said.