Emergency services have been searching for the two missing backpackers, both aged 20, since towels and other items of property were seen at the Shelly Beach boat ramp on Sunday evening.

The abandoned items were again found on Monday at 6am prompting police to search the missing men's silver Commodore Station wagon which yielded passports, wallets and other personal items.

Mid North Coast Police Inspector Peter Neville said three Marine Rescue vessels were involved in today's search, whole police divers searched submerged reefs and State Emergency Services scoured surrounding bushland and cliffs.

"This whole operation is about locating and rescuing these young men, from some of the discussions I've had this morning we honestly believe these people could well be alive," he said.

"At the moment this is strictly a rescue mission.

"At the moment the search extends three nautical miles off shore and predominately south to Lighthouse Beach at Tacking Point.

"Marine conditions have subsided somewhat today... at this point in time we have not put a time frame on the search, our efforts are entirely to locate these two men."

The families of Mr Palmer and Mr Ferrieux have been notified, while two friends have come forward and are cooperating with police, according to Inspector Neville.

"Two young women from overseas as well (have arrived), they were friends of the men and were in Sydney at the time," he said.

"They were due to meet with them in Port Macquarie - they have travelled here today to support not only operations but their friends.

"The families of both young men have been informed of what has happened in Australia and we have been able to keep them appraised of the situation."

Police are appealing to anyone who might have seen the men near the Shelly Beach car park or in the surrounding streets to contact them.

Mid North Coast Police District, Marine Rescue, SES, NSW Police Force Marine Area Command are all involved in the water, air and ground search.

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