Transport authorities have been ordered to assess the presence of asbestos at new sites in Sydney, after the potentially deadly material was detected in mulch at Rozelle Parklands earlier this year.
On Saturday, the NSW Environment Protection Authority issued two clean up notices for sites on the Sydenham to Bankstown rail corridor and the Prospect Highway.
Testing returned positive samples for asbestos in landscaped sections of the sites, it was revealed last week.
The notices require Transport for NSW and Sydney Metro to complete a detailed investigation and assess the presence of asbestos in any mulch used for landscaping purposes.
"As there is no public access and the use of these areas differs from the Rozelle Parklands, we have not mandated the removal of all recycled mulch at this stage," the EPA said in a statement.
"Remediation measures may be required depending on the outcomes of the reports."
Recycled mulch containing bonded asbestos forced the closure of several parts of Rozelle Parklands in the city's inner west last month, as well as other areas associated with the road interchange underneath the site.
Last month a clean up notice was also issued to the Transport for NSW, ordered it to remove all contaminated mulch from the site.
A clean up notice was also issued to parklands' mulch supplier, Greenlife Resource Recovery, requiring them to notify any other purchasers of the product.