Hundreds of kilograms of drugs have been seized and six people charged as part of an international investigation into an organised crime syndicate, the Australian Federal Police (AFP) has revealed.

The AFP said 230 kilograms of liquid methylamphetamine and more than 250 kilograms of cocaine was seized as part of a multi-agency investigation under Strike Force Polaris.

It said $156 million worth of liquid methylamphetamine was found in bottles of flavoured water that were on their way to a Sydney warehouse in December.

In January authorities in Bogota, Colombia, seized 243 kilograms of cocaine destined for Europe, police said, while in February a consignment of fresh flowers sent to Sydney from Colombia was discovered to have 10 kilograms of cocaine concealed in it.

On Tuesday police carried out 11 search warrants and arrested six people in Sydney.

Five Australians and one Colombian were charged with offences including importation of a commercial quantity of a controlled drug.

They appeared at Sydney Central Local Court on Wednesday and are due back in court in May.

AFP Detective Superintendent Mick Calatzis said the arrests were significant.

"We have cut the head off the snake – these are the key individuals involved in this criminal investigation," he said.

NSW Police, the AFP and Customs address the media in Sydney. ( ABC News: Alex McDonald )

Detective Superintendent Calatzis said Australian and Colombian authorities had been sharing information on the syndicate since May 2014.

He said a Colombian national allegedly involved in the syndicate was living in Sydney on a visa and studying English.

The Commander of Australian Border and Customs Protection Service in Sydney, Tim Fitzgerald, said the syndicate used both air and sea cargo to bring drugs into Australia.

"In relation to the flavoured water, it's not uncommon for us to come across that method of concealment where the narcotics are suspended in the liquid," he said.

"Then when it reaches here, technically someone is engaged to then dry out the liquid and you are left with whatever substance that was originally suspended in the liquid."

Commander Fitzgerald said the flowers were intercepted from an airfreight consignment through Sydney Airport.

"In this particular instance it wasn't necessarily the flowers, but the boxes that are used to transport the flowers or contain the flowers on their way here," he said.

"There is a number of methodologies used by syndicates. They will latch on whatever one they think is the hardest for us to identify."

Inquires into the syndicate are continuing.