A vendor transfers a box of seafood at a market in Shanghai on Saturday. Photo: Yang Hui/GT

Novel coronavirus has been detected on the outer packaging of imported frozen seafood products in Yantai, a coastal city in East China's Shandong Province, the local government announced Tuesday.

The products found in three companies of Yantai were from the same foreign cargo ship whose products first arrived in China via Dalian port, Northeast China's Liaoning Province. 

When reached by the Global Times Tuesday, the local epidemic prevention authorities in Yantai declined to reveal which country the foreign cargo ship came from.

Except for a small amount of the products, most are still in cold storage and have not entered the market, the Yantai government said in a statement on Tuesday. 

The Yantai Economic and Technological Development Zone has sealed up the contaminated products, and carried out disinfection at related enterprises and surrounding areas. 

All close contacts of the products have been tracked and quarantined, and their nucleic acid tests have all come back negative.

The three outer packages of the imported frozen seafood products first tested positive for the novel coronavirus on Sunday at Yantai's Economic and Technological Development Zone during a routine inspection of COVID-19 among frozen products and workers. On Monday, the local health authority in Yantai learned the results. 

Previously, Dalian customs on July 3 detected coronavirus on the inner wall of a white shrimp container and three outer packaging samples of frozen white shrimps imported from Ecuador. 

Dalian has also seen a clustered infection related to the local Kaiyang Seafood Company. The first patient worked in the processing and cold storage of imported and domestic aquatic products at the company.