WA police arrest 30 at Roe 8 site

West Australian police say they have arrested 30 people by 8am (WST) for disrupting land clearing works as bulldozers moved in on the controversial Roe 8 highway extension project.

Opponents to the project are challenging it in the Federal Court and arguing that it is destroying the unique Beeliar Wetlands, with protests in the last week including people sitting in trees to prevent works.

Those arrested had breached fences and trespassed, a police spokeswoman said.

The route is part of the $1.9 billion Perth Freight Link that aims to provide a better road between industrial areas and Fremantle Port.

Opponents said this week that tests had found asbestos was being released by land clearing so far.

"The senseless destruction continues to occur in Beeliar Regional Park, despite many non-compliance issues that the government have been made aware of including asbestos throughout the area," Rethink the Link spokeswoman Kim Dravnieks said.

"The Barnett government continues to underestimate the power of community to stand in unity against this appalling project on the eve of an election."