Tests have confirmed the existence of Panama disease Tropical Race 4 on a quarantined banana farm near Tully in far north Queensland.

Chief biosecurity officer Dr Jim Thompson said the results were from fresh plant samples from the same plot on the farm where the disease was first reported.

The banana farm was placed under quarantine earlier this month.

"These PCR test results are all positive, removing any doubt that we are dealing with Queensland's first case of Panama disease Tropical Race 4 on a banana farm," Dr Thompson said.

"This does not change our response. We will continue with our program of surveillance, sampling, tracing and diagnostics as we work to establish the extent of the disease."

Dr Thompson said they had been testing samples over the past week.

"We have been testing samples from a number of sites on the original property and connected family properties in the immediate vicinity, as well as one nearby property where we have traced the movement of equipment," he said.

"This is a standard precautionary process and at this stage there has been no confirmed detection of the disease outside the quarantined farm.

"Another type of diagnostic test is still continuing in Brisbane, which we hope will tell us what strain of Panama disease Tropical Race 4 we are dealing with."