Seventy-one schools in Australia’s capital Canberra were closed after laboratory testing found the decorative sand contaminated with chrysotile asbestos, the education department said.

“In line with our regulatory obligations, and in the interest of the safety of our students, staff and community we have decided to close some schools that have this product to allow for assessment clean-up and remediation to occur,” officials said.

Asbestos is a naturally occurring mineral fibre that was once widely used for construction because of its heat-resistant properties.

But studies have unearthed a clear link between lung cancer and long-term exposure to chrysotile asbestos.

Australia’s product safety watchdog said the risk was low as tests had so far not detected breathable fibres.

“The release of respirable asbestos fibres is unlikely to occur in its current state, unless the sand is processed by mechanical means such as crushing or pulverising,” it said.

“The risk that any asbestos found is likely to be airborne or fine enough for inhalation is low.”