A New Zealand couple has been captured on Ironbar security footage appearing to throw their bill under their table, before leaving without paying.

After realising what had taken place a staff member chased after the pair and led them back to the Ironbar to pay their bill.

Soon after, the lady in question took to Trip Advisor to vent her anger in a scathing attack on the Port Douglas bar.

This incident has raised the ire of Ironbar owner, Steve Hull, who, having witnessed the security footage, was left in little doubt of the patrons' intentions describing their actions as "intent to steal".

"These are middle-aged people and by their actions - by their smokescreen, by the bitter response in emails, and their hostile accusations of treating them like criminals (they are claiming innocence)...and when I go and find this footage, that really gets me stirred up," Mr Hull said.

A similar event took place on the same night at 2 Fish Restaurant Port Douglas where a $260 tab was left unpaid by a "dodgy duo".

"It rarely happens for us," said 2 Fish Port Douglas Restaurant owner, Jeff Gale.

"Most of the times that it happens people have calculated they can do it - they've entered the restaurant thinking they can run away quickly without paying the bill.

"The incident that happened the other night, we believe, was somebody who seemed to be unhappy with something - although they never told us.

"They did not realise that what they were in doing was, in fact, shoplifting," he said.

The pair was also tracked down and ordered to pay their outstanding bill.

"Let's hope they learn from the experience. Crime doesn't pay kids," a post on the 2 Fish Facebook page read.

Mr Hull said these instances can occur as frequently as once every two weeks, resulting in losses in the thousands of dollars each year.

"The margins that are in food for restaurants is very small, and this sort of stuff just kills you at the end of the day.

"I'd really like to know from all the restaurants and the resorts whether it's increasing, and whether these people are becoming more professional at it.

"It's not something we talk about between restaurants...it's stealing, that's what it is."