Vic dry cleaning factory goes up in smoke

It took 50 firefighters nearly two hours to bring a factory fire under control in Melbourne's north overnight.

Crews had to beat a hasty retreat from inside the dry cleaning factory in Campbelfield late on Friday after the 100-metre long concrete building became structurally unsafe.

Firefighters then used a cherry picker and teleboom hose to battle the blaze from above.

"Two appliances will remain on scene throughout the night to complete the extinguishment of the fire," an MFB spokesman said in a statement on Saturday morning.

"A cause has not yet been determined."