Human bones have been discovered as part of the Peka Peka to Ōtaki Expressway excavation works.
NZ Transport Agency senior manager Andrew Thackwray said the discovery was made on June 12.
"Work was immediately ceased, the site closed and the accidental discovery protocol was actioned, as outlined within the contract consent conditions."
It was important to the agency that, as tangata whenua, Ngā Hapū o Ōtaki decided tikanga with regards to the discovery, he said.
"This protocol has been developed alongside ngā hapū to ensure correct cultural processes are followed when accidental discoveries like this are made.