Brisbane restaurateurs are putting the word out after being allegedly scammed for free meals and drinks by a group of Irish travellers.

The alleged scammers - apparently a group of young men and women with kids - are accused of planting glass in their meals to deceive horrified restaurant owners and servers.

Former Hot Plate winners Emi and Marie, who run two Japanese restaurants called Birds Nest, are two victims of the brazen scheme.

Marie and Emi run two Japanese restaurants called Birds Nest, and were targeted by scammers.

"They were three ladies, somewhere between 20 and 30," Marie told A Current Affair .

"It was a little hard to tell as they had heavey make-up, made up hair, not wearing much clothing."

She said it was at the end of the meal that the customers turned nasty, "screaming" they had found glass in their food.

The scammers drop a piece of glass into their meal and claim it is the restaurant's fault.

Marie said she was suspicious and told the the diners she was "pretty certain" it hadn't come from their kitchen.

"The three of them were ganging up on me, yelling (that) their children had eaten this food," she said.

"They were horrified, they were traumatised."

Mark from Creole kitchen waived a $300 bill after falling victim to the scam.

The group insisted on staying for free drinks.

Marie said the bill eventually came to $250.

But a week later she learned other businesses had been targeted in a similar scam, after a photo of the group was posted online.

Police are investigating the alleged scammers.

Mark, who runs the Creole Soul Kitchen in Brisbane's Spring Hill, waived a bill of close to $300 after the same glass trick was played on him.

He said he reported the incident to the health department and was in fact relieved to hear he had been the victim of a scam.

"These are things that can damage small restaurants," he said.