One of two giant tunnel boring machines digging the new Perth Airport rail link has been temporarily shut down.

TBM Grace is one of two machines boring out an eight kilometre tunnel for the Forrestfield-Airport Link project.

A Perth Airport spokesperson said this week that TBM Grace was halted “due to some ground disturbance issues”.

The Public Transport Authority (PTA) says TBM Grace was stopped on February 14, and is now waiting on a report from international experts before resuming work.

Authorities have not gone into detail on what kind of “ground disturbance” issues had been detected.

“Tunnelling work by TBM Grace for the Forrestfield-Airport Link — which has not yet reached any critical infrastructure — has been temporarily suspended,” an airport spokesperson told reporters.

“There has been no threat to public or worker safety.”

The “disturbances” occurred on Perth Airport land.

A PTA spokesperson said the nature of the terrain presented some challenges to the project, but the authority is confident it will not lead to significant delays.

WA Premier Mark McGowan said he had not received advice saying there was a risk to the public, or that the ground disturbances were “serious”.

“Whenever you do a major construction contract things happen but obviously, obviously we are not going to compromise anyone's safety at the airport,” he said.

“We're not going to take any risks. We'll take the best advice in relation to these issues.”

Despite the tunnel borer doing nothing for almost five weeks, Mr McGowan said the project was still on time, because the tunnelling was ahead of schedule.