The Australian Border Force (ABF) has detained 34 Malaysian citizens, including two children, working on a blueberry farm north of Coffs Harbour.

The farm is allegedly part of an underground labour hire syndicate, hiring illegal foreign workers in the coastal town of Woolgoolga.

On Tuesday ABF officers and Australian Federal Police executed a search warrant on the property after receiving a tip-off from a member of the public.

They discovered 34 Malaysian citizens working on the farm; 14 were in the country illegally and another 20 were working in breach of their visa conditions.

The adult detainees were taken to Villawood Immigration Detention Centre to be sent back to Malaysia, and the children were transferred to an alternative place of detention.

Minister for Immigration and Border Protection Peter Dutton said the labour hire crime ring was the subject of a criminal investigation.

"[This] operation sends a strong message to individuals and syndicates involved," he said.

"If you are in Australia without a valid visa, if you work in breach of your visa conditions or if you are exploiting foreign workers, you will be caught."

Federal Member for Page Kevin Hogan said he did not believe the Mid North Coast to be a problem area for illegal workers.

"It is certainly widespread around the country … I haven't heard of a lot of it in our region," he said.

"There are certain syndicates who specialise in this and we want to crack down on those … I'm certainly glad that there's been a crackdown in this case."

He said the penalties for exploiting foreign workers, up to $54,000 for a corporation, were appropriate in the circumstances.

"These people are exploiting children," he said.

"The employers are doing this consciously and they need to be fined because of it."

Organisers of visa fraud and illegal work face up to 20 years' imprisonment or fines up to $100,000.