Koroit police Sergeant Pat Day said people were clean out old sheds when they came across old blasting sticks of explosives.

"WorkSafe came out on January 3, removed the explosives and then carried out a controlled detonation out in a paddock the next day," he said.

Sergeant Day said the six sticks of AN60 ammonium nitrate were covered in brown paper and included detonator cords.

"They were hanging from a rope in a shed roof for the last 30 years," he said.

"The explosives were delicately removed and then WorkSafe returned next day and detonated them."

Sergeant Day said he had been told by an arson chemist that really old explosives were "really dangerous", sweated and formed crystals which made the substance unstable.

"People should not go anywhere near stuff like this,” he said. 

“The owner contacted us and asked what to do. We were out there for two days.

“It’s very dangerous to grab and move old explosives. It was detonated 300 metres away and threw up dirt everywhere,” he said.

A WorkSafe Victoria spokeswoman said that explosives were used in many workplaces, such as mining, quarrying, civil construction and agriculture. 

“There are strict rules governing their use, storage, transport and disposal.  For information contact WorkSafe’s advisory service on 1800 136 089,” she said.