Three more Melbourne parks are closed after traces of asbestos were found, bringing the number of parks impacted by the toxic fibres to five.
Hobsons Bay City Council said it had closed three reserves on Friday after testing confirmed the presence of "asbestos-containing material".
The impacted parks are Crofts Reserve, Hosken Reserve and Lynch Reserve, all in Altona North.
"Recycled mulch from these reserves was sent for testing following the recent findings at Donald McLean Reserve in Spotswood," the council said in a statement on Friday evening.
"Council will work with a material hygienist and the Environment Protection Authority Victoria to conduct remediation works on all these sites."
The discovery comes after fragments of asbestos mixed with mulch and other building materials were discovered by a father on Monday in the same council area at the Donald McLean Reserve in Spotswood, west of the CBD.
The Victorian Environment Protection Authority tested mulch products from the producer who supplied the material at the reserve and did not find any asbestos.
"While its investigations continue, EPA believes that the issue is localised to Donald McLean Reserve and that the source of asbestos and other contaminants at the site was illegal dumping of construction and demolition waste that occurred after the mulch was delivered," a spokesman said in a statement.
Regulators just hours before cleared samples from other parks in the area with mulch from the same source as Donald McLean Reserve.
"Testing results have confirmed the only site with traces of asbestos is Donald McLean Reserve," the spokesman said.
"Material from all other sites tested negative for asbestos."
Hobsons Bay City Council said a safety auditor regularly inspected all playgrounds in the area
Contaminated soil was also detected at a park at a different Hosken Reserve in Coburg North, north of the CBD, as the park underwent upgrades.
A Merri-bek City Council spokeswoman confirmed on Friday asbestos was first found at the site in late January.
"During more recent landscaping works, further asbestos-contaminated soil was discovered," she said.
"This contaminated soil is now being removed by competent and qualified asbestos removalists and is expected to be completed by Friday, May 31.
"Any soil that contains asbestos is also currently sealed, under cover and is inaccessible to the public."
The reserve has been closed to the public since January due to the upgrades.
The council said all asbestos found on site was considered non-friable, meaning it was solid and could not be crumbled or released into the air.
It also said there was no evidence to suggest the incident was related to any other asbestos cases.
The protection authority said the risk to the community was low.
Victorian minister Vicki Ward said the government was taking the discoveries seriously but wouldn't be drawn on whether it would set up a NSW-style task force to investigate if the issue was widespread.
"The EPA are ... investigating and will continue to monitor this closely," she told reporters on Friday.
Victorian Liberals deputy leader David Southwick said the government must ensure kids can play safely in public spaces.
"It doesn't seem right that the government are allowing these things to be discovered just by chance," he said.
The South Australian Environment Protection Authority will undertake further inspections of mulch producers to ensure the issues in NSW and Victoria are not replicated in SA.
Tasmania's WorkSafe and Environment Protection Authority is conducting joint site inspections of mulch producers to identify any potential for product contamination.
The Victorian authority has already conducted precautionary inspections of 59 commercial mulch producers and found no traces of asbestos.
Testing was triggered after fragments of bonded asbestos were detected in Sydney's Rozelle Parklands in January followed by positive detections in Queensland.
