Environment watchdog officials will be at the site of a west Melbourne plastic recycling plant for days, after a blaze forced workers to evacuate.
Emergency crews were called to the Laverton North SKM plant on Monday evening and found a "deep-seated fire" in a machine that was surrounded by tonnes of waste.
Environment Protection Authority officials, who are investigating the matter, believe the fire involved a conveyor belt.
"Officials will be there regularly over the next couple of days," an EPA spokesman told AAP on Tuesday.
The EPA is investigating the matter. Meanwhile, firefighters handed back the site to its owners, allowing it to resume operations.
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More than 40 firefighters tackled the blaze, with a rescue unit and two aerial units.
It took 45 minutes to bring the fire under control, with the machine involved "surrounded by baled waste".
The EPA issued SKM a remedial notice to stop accepting recycling waste at its Laverton North plant in February due to fire risk, but the firm was allowed to resume accepting the waste after meeting conditions of the notice a month later.
