Police in NSW found and seized more than 300 kilos of a chemical used in making "ice" hidden in frames of shipping containers.

The containers hiding pseudoephedrine worth $75million were found in business sites in the state, including Bathurst, Tamworth and Curlewis. The owners of the businesses that bought the steel containers, however, were unaware of the hidden substance and were just using the containers for storage on farms.

The two empty containers found in Tamworth and Curlewis have been there for three months with the drug ingredients were still intact. The pseudoephedrine were inside metal tubes hidden in the containers' frames.

Each container, which was being used for storage, contained about 15 kilos of pseudoephedrine, Detective Inspector Steve Patton of the State Crime Command's drug squad said, according to the Northern Daily Leader. "The drugs were concealed in such a manner that they could not be seen and the alterations to the container would not be noticed unless the container was closely inspected. A hole was cut in the frame of the container to extract the drugs."

The NSW Police, with help from the Australian Customs and Border Protection Service, have been tracking 20 containers from China used by drug smugglers to hide pseudoephedrine. The search started after police acting on a tipoff found the ingredients for ice or methylamphetamine concealed in four containers at a container yard at Chipping Norton outside Sydney on Dec. 7.

Police speculates that the drug smugglers lost track of the containers, which were emptied before sold to other businesses.

Patton said they have suspects linked to the hidden drugs but are not yet naming them.