DRUG sample safety concerns saw a Brisbane judge on Monday delay the sentencing of three men involved in a Mackay cocaine importation ring.

Crown prosecutor Aaron Guilfoyle told the Supreme Court that authorities were trying to overcome logistical issues regarding the safe transportation, delivery and storage of samples of the drug to a laboratory in Brisbane for defence counsel-requested testing.

Colombian men Juan Pablo Ocampo Alvarez, 29, German Rendon Alvarez, 47, and Alexis Giovany Gomez Ruiz, 35, pleaded guilty to their involvement in the drug operation that was allegedly masterminded by a Mackay man.

Ocampo Alvarez, Rendon Alvarez and Gomez Ruiz were not required to front the court for Monday's brief mention.

The Crown is expected to report back to the court on Friday with an update on where the drug delivery process is at.

The man accused of overseeing the importation of about 20kg of cocaine in oil barrels from South America to Mackay between 2009 and 2011has disappeared.

- APN NEWSDESK