Suspicious Melb fire at Hard Yakka factory

A blaze at a disused Hard Yakka factory in Melbourne has been deemed suspicious but the cause is yet to be determined.

Fire investigators are at the factory after the blaze on Sunday night when crews found "smoke billowing from the factory and shooting through the roof", the MFB said in a statement.

The fire was brought under control within an hour and a search of the building found no one inside.