An asbestos contamination in Sydney widened on Sunday, with authorities saying the toxic material had been detected in more schools, as a weeks-long effort continued to remove it from mulch used in public places.

The contamination was discovered in January when asbestos was found in a playground in the New South Wales capital, and a subsequent probe found it in recycled mulch near the park, built above an underground road interchange.

In an update on the contamination on Sunday, the state's Environmental Protection Authority (EPA) said 34 city sites had now returned positive for bonded asbestos.

HEALTH CLINIC IN MONTANA SUPERFUND TOWN THAT SUBMITTED 300 FALSE ASBESTOS CLAIMS FACES PENALTIES

New sites where asbestos had been confirmed were two schools in the city's west, the EPA said, lifting the number of schools confirmed as tainted to four.

"There is ongoing testing at a further four schools," EPA head Tony Chappel said, adding that testing was also underway at a hospital and in part of the city's vast Royal National Park.

The agency on Saturday said a public school, park, and two part-built housing estates were tainted, while transport projects, a warehouse and a hospital have also been confirmed as impacted.

In response, the state government has set up an asbestos task force to give more resources and support to the EPA, in the agency's largest probe since it was established in 1991.

Asbestos became popular in late 19th century as a way to reinforce cement and for fire-proofing, but research later found that the inhalation of asbestos fibres could cause lung inflammation and cancer. It is now banned in much of the world.