Vic factory collapsed during fire

A central Melbourne factory has partially collapsed after being engulfed by fire.

The blaze, in North Melbourne, started early on Monday and is continuing to burn.

The single-storey factory was completely engulfed when firefighters arrived about 7.20am and part of the rear of the building had collapsed.

Crews are attacking the fire with hoses as they try to protect neighbouring buildings.

Surrounding suburbs have been cloaked in smoke.

No one has been injured.