The Otago Regional Council will not share publicly the evidence it used to identify McKeown Group Ltd as the source of fuel contaminating Oamaru Harbour.
"We are not commenting further, as the matter is subject to an enforcement process," a council spokesman said this week.
McKeown Group Ltd was last week issued an abatement notice and required to install warning signage at the harbour, remove underground petroleum storage tanks, dispose of petroleum and impacted groundwater from within monitoring bores and mitigate any further contamination of the coastal marine area.
However, McKeown Group managing director Ken McKeown told the Otago Daily Times he did not believe his company was responsible for the oil sheen.
Oamaru Harbour was well used by the petroleum industry in the 20th century.
The discharge was likely to have a series of adverse environmental effects but pose low toxicity to humans, the council said.
