The operators of a large recycling plant in Melbourne say they're "concerned" how a second blaze in a year started at the site and will work closely with investigators to determine the cause.
Bales of recycled material at SKM Recycling, in Coolaroo, began smouldering on Saturday night, nearly a year after a major blaze at the plant which burned for 11 days.
Saturday's fire in a shed was extinguished just before midnight after an advice message issued to surrounding suburbs due to smoke.
The Environmental Protection Authority, heading a task force looking at recycling stockpiles which pose a fire risk, will remain at the site on Sunday.
In a statement to AAP, SKM Recycling said employees at the plant on Saturday noticed recyclable material smouldering in the corner of a shed.
"Since last year's fire, SKM has worked hand-in-hand with the EPA to ensure a major fire event like that can never occur again," the company said.
"Even so, we are concerned about how any incident like this could occur and will be working closely with Victoria Police, MFB and the EPA to review video footage and assist in their investigations."
SKM was last year hit with a class action from a group of residents who claimed the July 13 fire caused health problems and damaged homes.
It cost at least $4 million to remove 30,000 tonnes of burnt waste from the site.
A government audit released in December found that some of the state's recycling plants were ill-equipped and poorly prepared to prevent fires.
Two recycling centres at Wantirna South and Laverton North caught fire in April and February, respectively.
A worker from an aged care home close to the Maffra Street plant on Saturday night told AAP she could smell smoke outside, but could not see the flames.
SKM Recycling has been the subject of six legally enforceable notices and 28 EPA inspections since last year's fire.
The MFB said Saturday's incident was much smaller than last July's blaze, but it still involved 70 firefighters and 14 appliances and took hours to extinguish.
Australian Associated Press