SYDNEY -- The environmental watchdog in the Australian state of Victoria said on Monday that investigations are ongoing into the source of mulch, as more sites were found containing potential asbestos.

According to the statement by the Environment Protection Authority (EPA) Victoria, testing results are expected to come out on Tuesday after the regulator completed inspections at seven parks across two metropolitan councils during the weekend.

The EPA Victoria called on all councils across the state to assess quality controls for landscaping works and supply contracts for garden mulch, while also reminding demolition companies of their environmental compliance obligations in relation to asbestos management.

These moves came after the Hobsons Bay City Council closed down a playground at Donald McLean Reserve, as the cancer-causing substance was discovered in recycled mulch earlier this month.

"EPA yesterday issued Hobsons Bay City Council with two remedial notices, ordering proactive inspections of more parks and gardens in its area as well as requiring further information from the council," said the regulator.

"EPA requires Hobsons Bay City Council to investigate the nature and extent of any harm or risk of harm to human health arising from asbestos in reserves or land areas managed by the council," it added, also demanding the council to provide a list of all suppliers used to source mulch, its contractors and subcontractors.

The environmental authority confirmed that the asbestos identified across the state is bonded, which poses less danger than the friable one.

"Bonded asbestos is generally made up of a small amount of asbestos fibers that are tightly bound in a product such as resin or cement. It is considered low risk for people who are in contact with it, unless damage or bad weathering means that asbestos fibers can be released into the air," the EPA Victoria noted.