An anti-mining protester and mine company staff have clashed as work begins at a controversial mine near Waihi.
New Talisman Gold Mines started a $2.2 million project prospecting for gold and silver at Mt Karangahake on Tuesday.
Company chief executive Matthew Hill said security staff called police after an incident with a protester on Thursday morning. It involved a male protester trying to drive through a gate that was being closed.
A police spokeswoman confirmed officers were called to a mine access road just before 8am.
One person had made an assault complaint but no one was seriously injured. Police were investigating and no charges had been laid.
Duncan Shearer, chairman of anti-mining conservation group Protect Karangahake, said he was not present when the incident occurred.
He had spoken to group members who were there to monitor mine traffic and who witnessed what happened.
The protester involved in the gate incident had been following a line of vehicles and the gate was "hastily" shut in front of the man's vehicle, he said.
The person involved was connected to the group but acting on their own initiative on this occasion, he said.
Mr Shearer was upset to see mine operations start and said protesters were in it for the long haul.
"This mountain is important to us and we intend to continue opposing mining in this iconic and precious piece of conservation estate."
The group wanted to ensure their voices were heard "peacefully and legally".
A peaceful protest was held on the access road on Wednesday, he said.
A group of locals linked arms and walked slowly in front of vehicles leaving the site.
Mr Hill, of New Talisman Gold Mines, said the company's security staff also reported that incident to police.
"These are workers just trying to get home to their families. We are a small company and we just want to get on with our work."
The protests had been annoying but he did not want to see the situation escalate, he said.
Opposing positions: in a nutshell
The land is first and foremost conservation land. It should be protected and conserved for everyone's enjoyment, not exploited for the profit of a few. Mining has no place there.
Mining company perspective
The mine has been there for a long time, and has historically been productive. The company has appropriate consents to carry out its work, including closing the mine site at the portal to the public for health and safety reasons.