More than 50 firefighters are battling an out-of-control blaze at a food processing factory  in Melbourne's south-east.

Firefighters were alerted to the factory fire in Bond Street, Mordialloc about 5pm on Wednesday.

Crews arrived at the scene within seven minutes to find the single storey tin factory ablaze and thick, black smoke billowing across the sky.

A Watch and Act has been issued advising the community to stay indoors, close their doors and windows, and turn off any heating and cooling systems.