Police spent the weekend searching for a man believed to have been separated from the party but said on Sunday afternoon he'd been located on a track near Truscott Air Base on Mitchell Plateau in the state's far northern reaches.

They confirmed he had been part of the group which had "arrived to Australia via an unknown vessel".

The opposition seized upon the incident as evidence illegal asylum seeker activity is again on the rise, with two similar arrivals since November.

Opposition foreign affairs spokesman Simon Birmingham said it concerned him that the boat had apparently offloaded its passengers and been able to depart without detection.

"It comes at a time where evidence to Senate committees ... is that we have a reduction in relation to maritime surveillance, a reduction in relation to aerial surveillance, concerns about the future budget projections for Operation Sovereign Borders and a government that dismantled temporary protection visas," he told ABC's Insiders.

"The government needs to acknowledge if there are increasing failures here, those problems, their responsibility and act to fix them."

However, Mr Albanese said was important to note there had been no change to Operation Sovereign Borders.

"Once again through the response of the Australian government, that message will be sent very clearly again to the region," he told reporters in Melbourne.

"We have a very large coastline. What is clear, though, is that people who are unauthorised arrivals won't be settled in Australia. Operations sovereign border principles will apply as they have been in this case."

WA police said the search for the missing man had been conducted in challenging terrain but he'd been found in relatively good condition.

Despite media reports suggesting the group he was with - as many as 15 individuals in total - had come from China, no one has confirmed their origin or number.

Australian Border Force said in a statement it did not comment on operational matters.

The latest arrival comes after a group of 39 people from Pakistan and Bangladesh were found at Beagle Bay, north of Broome, in February after they also came by boat.

The group was flown to an offshore detention centre on the Pacific island of Nauru.

Coalition home affairs spokesman James Paterson said the incident was the 13th time since the last federal election a boat had undertaken to bring asylum seekers to Australia.

"It's no surprise why," he said.

"Aerial surveillance hours under the government's watch have dropped 20 per cent, maritime patrol days have dropped 12 per cent.

"The result of that is people are getting through, they getting on shore and our border protection regime is being undermined."

Australian Associated Press