Health authorities say contact tracers could not identify all close contacts at a large construction site linked to a cluster on the New South Wales Central Coast because the site had incomplete check-in data and inadequate records.

Anyone who visited the KI Building Services development at North Gosford on August 20-27 is considered a close contact.

The Central Coast Local Health District (CCLHD) said seven cases had so far been linked to the site.

A spokesperson said venues were published on the NSW Health website when "an exhaustive list of those at risk [could not] be determined".

"A review of Service NSW check-in data for the KI Building Services site at 5 Ormond Street, North Gosford, indicated incomplete data and inadequate records," the spokesperson said.

The CCLHD said police were informed and are undertaking ongoing compliance checks and inspections of the site.

Police said they conduct daily COVID compliance checks at a range of businesses to ensure organisations are following COVID safety plans and adhering to the Public Health Orders.

The ABC has attempted to contact KI Building Services for comment.

'Industry doing all it can'

Since the lockdown began in June, several COVID-19 cases on the Central Coast have been linked to both local and Sydney-based construction sites.

Brian Seidler, executive director at Master Builders Association of NSW, said sufficient measures were in place at building sites that the organisation had been dealing with including contact tracing, rapid antigen testing, worker permits, and vaccinations.

"The industry is doing all it can to curtail any outbreaks … we have been doing it for a year and a half now," Mr Seidler said.

"Yes, we're going to have some active cases found on building sites, but what we're trying to do is shut them down as quickly as possible.

Mr Seidler said the association was gathering information on vaccination rates in the industry.

"It's now more about the vaccination regime applying to building workers," he said.

"The more that are vaccinated in our industry, the more we should be able to work.

"I understand there's thousands now who have been vaccinated and certainly there are pockets of the building industry requesting … if you want to work on certain building sites you're going to have to be vaccinated."

He said the association had been in discussions with the NSW government about ways the industry could fully open up as quickly as possible.

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