The Australian Federal Police have seized 4 million MDMA tablets during a raid on a storage facility in Hornsby.
It is estimated the drugs amounted to 1.2 tonnes and had a street value of $145 million.
The seizure is the AFP’s largest drug haul for 2016.
Two Polish nationals have been arrested and will face court today.
Border Force Commander Tim Fitzgerald said the drugs came from Czechoslovakia and the syndicate went to extreme lengths to conceal them.
“The goods were declared as aluminium rolls and within the aluminium rolls there was a number of lead casings that concealed the actual narcotics themselves, so it’s a very sophisticated concealment,” he said.
The raid was part of a joint operation with the Australian Border Force.