Five Vietnamese asylum seekers are still at large after escaping from the Yongah Hill immigration detention centre east of Perth on Saturday.
It is believed they scaled a razor wire fences , but the department has not shed any light on how that was possible.
Western Australia Premier Colin Barnett said it was not clear whether the men received outside assistance.
AAP reports Northam shire president Steve Pollard wants a personal briefing from the department about the escape.
"If it had've been one person who was smuggled out on a truck or something, you could understand that, but five people going over a couple of fences is a little bit unbelievable," he said.
The department said the missing men posed no risk to the community.