"We are currently unable to provide any further information. Our primary focus at this time is to support the family and workmates affected by this tragedy."
They also said: "Providing a safe workplace is a priority for Fulton Hogan and is a core value of the company."
The busy route is used by trucks heading to North Port and has been undergoing repairs.
New Zealand Transport Agency acting Northland Highway manager Paul Glucina said there had been ongoing resealing work at various locations along SH15 during the past month and the worksite where the fatality occurred was part of that work.
"We're deeply saddened by this fatal accident in Northland, and our thoughts are with everyone affected by this tragedy."
Worksafe had also been notified and were investigating.
The death takes Northland's road toll for the year so far to 15 deaths from 12 crashes.
In July last year a 127km stretch of road, including Otaika Valley Rd, became part of Northland's State Highway network.
The New Zealand Transport Agency became the new administrator of the route named State Highway 15, which runs from Kaikohe to Marsden Pt, providing access between about 50,000ha of production forest and North Port.
The road was formerly the responsibility of Far North and Whangarei ratepayers.
Chairman of the Northland Regional Transport committee, Northland regional councillor John Bain said the fatality was a tragedy but brought to the fore the need for urgent maintenance on that road.
He said SH15 was due for upgrades but that could only take place when it progressed through the national planning process at NZTA.