Authorities will address the media in Sydney on Tuesday morning, a week after they began an investigation following an international agency flagging suspicious offshore activity by a foreign fishing vessel.

The three crew members - a Hong Kong man aged 40 and two Australian males aged 27 and 32 - were screened for coronavirus before they were decontaminated by hazardous materials firefighters.

The trio were charged with attempting to import a commercial quantity of border-controlled drugs and failing or refusing to disclose identity as required.

If convicted, they face life in prison.

All three were refused bail in a Sydney court on Monday. They will appear in the same court on October 14.

Border Force's marine command allegedly found the vessel Coralynne approaching the foreign fishing ship "and making an alleged at-sea transfer of illicit drugs bound for Australia".

On Saturday the NSW Police Marine Area Command vessel Nemesis intercepted the Coralynne, arresting three people on board and identifying the alleged drugs.

Presumptive testing of the substance returned a positive reading for cocaine.

By Sunday night the Coralynne had been towed to Balmain, where specialist marine police began their investigations.

"While the exact weight and purity of the seized substance is to be confirmed, investigators will allege the illicit drugs were stored in the engine room," authorities said in a statement.

Police also searched properties in the Sydney suburbs of Chatswood, Zetland and Glenbrook.

Australian Federal Police Assistant Commissioner Eastern Command Justine Gough said the investigation shows authorities were working together to break up the drug trade.

"Our ability to work together using the resources and expertise of each of our agencies has again prevented the importation of illicit drugs into our community," Assistant Commissioner Gough said.

"We are committed in our efforts to identify and disrupt illicit drug supply chains and cause maximum damage to organised crime business models."

NSW Police State Crime Commander, Assistant Commissioner Stuart Smith said the arrests were a warning to organised criminal syndicates "that if you wish to take advantage of the community through illegal activity in NSW, law enforcement agencies in Australia will work together to dismantle your operation."

"The efforts of officers, including those from the Marine Area Command, to tackle 3.5 metre swells to ensure this illicit cargo didn't reach our shores and those we alleged are responsible were put before the courts should be commended," Assistant Commissioner Smith said.

Investigations are continuing both locally and internationally.

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