A man accused of lacing a workplace milk bottle with anti-freeze is standing trial in Whangarei District Court

The district council animal manager worker is charged with poisoning - with intent to cause grievous bodily harm.

Open justice reports Clinton Sullivan's colleague at the pound found the green-coloured milk while making a coffee.

The court's heard the man thought it was a prank with food-colouring - but tasted chemicals when he drank the liquid.

Managers went through a process of elimination to determine what was in the milk, revealing anti-freeze creates the same green tinge.

The trial is expected to last three days.