"These are high risk environments ... The repeat illegal actions of these individuals puts the health and safety of our people and the activists themselves at risk."
Those to receive the notices included Dunedin-based Oil Free Otago spokeswoman Rosemary Penwarden, who told the Otago Daily Times the move was "very peculiar".
The notice banned her from entering 19 sites related to OMV, including its offices in New Plymouth and Wellington, but also the Maui A and B platforms, located off the Taranaki coast.
The list did not include any Dunedin sites, but did include the COSL Prospector drilling rig and support vessels, currently located 146km south-east of Balclutha.
"I would have to be super-gran to board all of those.
"If OMV are worried about a 51kg grandma disrupting their multimillion-dollar projects they really are in a bad way.
"Do OMV think a trespass notice will frighten me? If so, I'd like to remind them that we Kiwis have a strong tradition of standing up to the big boys.
"When the things we love are threatened we do not back down."