Tamim Jamaal Nozhat, a former building company director, was arrested in December 2017 after months of investigations by the Australian Federal Police.

He pleaded guilty on Tuesday to one charge of importing a commercial quantity of a border-controlled drug. The ecstasy had an estimated street value of more than $40 million.

At the time of arrest, police said Nozhat was the intended recipient of a consignment of pool chlorine sent from Hamburg, Germany, destined for a Fyshwick warehouse.

However when the consignment of eight cardboard boxes containing 144 buckets was searched by Australian Border Force, officers found vacuum-sealed bags of an off-white crystal substance hidden among the chlorine.

Tests proved the substance to be MDMA, weighing 356 kilograms.

Police documents stated Nozhat had leased the Fyshwick warehouse and had set up a pool company where he was listed as a sole trader.

Police said at the time that the operation was the most significant drug bust for drugs headed to the ACT.

Nozhat had entered a plea of not guilty to the charge earlier on in the court process, but after agreements were made between his defence lawyers and prosecutors he pleaded guilty.

A jury had been selected to hear Nozhat's trial, but jurors were discharged by Justice David Mossop once Nozhat pleaded guilty and the trial was abandoned.

Justice Mossop thanked the jury members for their willingness to be part of the judicial process, saying service on a jury was essential to the administration of justice.

Several matters from the case will now be heard by Justice Mossop before Nozhat is sentenced.