Both men declined to say anything further after replying "guilty" when asked how they would plead to their charges.

Justice Declan Kelly adjourned the matter until a suitable date could be found where both the brothers' barristers would be available for a sentencing hearing.

Dru and Nathan Baggaley returned to custody ahead of their sentencing.

Dru Baggaley and another man were intercepted by the navy in July 2018 after using a seven-metre inflatable boat to pick up 650kg of cocaine from a ship 360km off Australia's east coast.

Dru Baggaley was seen by navy surveillance jettisoning parcels into the sea, some of which washed ashore at various locations off the east coast of Australia.

The inflatable boat, which was launched from Brunswick Heads on the NSW north coast, had been purchased by Nathan Baggaley and registered in his name.

The brothers were previously found guilty of attempting to import cocaine by a Brisbane Supreme Court jury in April 2021.

Dru Baggaley was sentenced to 28 years' imprisonment and his brother 25 years.

They both later won appeals against their convictions and were ordered to face a retrial that was due to start on October 28.

The Court of Appeal in 2023 found Dru Baggaley was not given the sufficient opportunity at trial to respond to allegations that he had been in possession of an encrypted phone that had received messages from a user named "Thunderbutt" about organising a cocaine import.

The court this year found Nathan Baggaley's conviction was unsound as the jury was not properly instructed to avoid its guilty verdict from being dependent on his brother being found guilty first.

Nathan Baggaley won two silver medals at the 2004 Athens Olympics along with three world titles.