The containers, that were supposed to be each transporting about 25 tonnes of 99% copper-content blister, were inspected by customs personnel last week, according to photographs seen by Fastmarkets.
Two industry sources told Fastmarkets that the containers had been filled with stacks of red cement bricks and have now been impounded at the port.
The seals on the front of the containers were intact at the point of inspection, the sources said, while the copper is believed to have been stolen by thieves who broke in from the side of the containers.
At current copper prices, the containers were carrying more than $500,000 worth of copper.
The containers are said to have been booked by a major commodity trading house, who declined to comment on the incident when contacted by Fastmarkets.
Approximately 75 tonnes of blister copper had been scheduled to be delivered to its Chinese copper smelter client via Lianyungang port to be processed into copper cathode.
Chinese copper smelters that use Lianyungang port include Sanmenxia, Yuguang Gold Lead, Baiyin Nonferrous and Jincheng.
The port authority of Lianyungang did not respond to inquiries from Fastmarkets at the time of publication.
Fastmarkets reported a similar incident in August where containers of copper cathode from Africa were found to be filled with sand upon arrival in China.
The containers of copper cathode, which belong to two parties - one Africa-based copper producer and one Asian trading house - were broken into at the port of Beira, according to a source with direct knowledge of the matter at the time.
And an Asia-based trader also mentioned hearing of a copper shipment from Pakistan containing iron slabs and cement among the ingots in the past two months.
These reported incidents come after a copper price rally in recent months. The London Metal Exchange three-month daily official copper price was $6,800.50 per tonne on September 15, the highest since June 2018. It is up 47% from the lowest point this year of $4,626.50 per tonne on March 23.
On higher spot availability, Fastmarkets’ copper blister 98-99% refining charge spot, cif China went up slightly to $135-160 per tonne on August 28, from $135-155 per tonne at the end of July.
Three containers of copper from Turkey heading to a Chinese smelter have been discovered to have been filled with bricks upon arrival in Lianyungang port in China, sources have told Fastmarkets.