Jon Downing said the Alderdice Brassfoundry had been operating for well over 100 years but had been fortunate to not sustain significant fire damage overnight Wednesday.

He said waste paper from a skip bin had been jammed into the old wooden door of the supper room and been set alight.

Fortunately the fire did not catch at the rear of the Henna Street premises.

The fire comes after a series of ​deliberately lit blazes at public toilets around Warrnambool during the past six months.

An arcade off the Lava Street Coles car park is currently closed due to fire damage after a fiberglass statue was set alight.

Mr Downing said it was concerning that a series of fires had been lit around the city.

"I would ask that anyone sees people in places where they shouldn't be late at night to contact Warrnambool police," he said.

"This was a very old building and it could easily have suffered enormous damage. We were very lucky," he said.

Detective Senior Constable Ashlea Witham, of the Warrnambool police ​crime investigation unit, ​requested that anyone with information about the arson attempt contact the Warrnambool police station or Crime Stoppers on 1800 333 000.

She said police had been investigating a series of deliberately lit fires in Warrnambool.

The detectives said it was believed that at least some of those fires were related.

"This is very concerning behaviour," she said.

"The fire at the arcade has caused a significant disruption to businesses.

"Anyone with information is requested to urgently contact police."

Detective Senior Constable Witham said the potential for significant damage was high at the brass foundry.

"We're talking about a very old building and someone has deliberately  tried to set fire to it," she said. 

"This is high-end serious offending and anyone involved will be prosecuted to the full extent of the law," she said.