Inspectors of Guangdong Medical Devices Quality Surveillance and Test Institute register face masks for quality test in Guangzhou, south China's Guangdong Province, April 2, 2020. (Xinhua/Li Jiale)

Chinese customs officers in Ningbo city, Zhejiang Province, seized a batch of 390,000 surgical masks bound for the US due to non-conformity issues, in one of the first such cases since China tightened export screening to ensure quality of its medical exports. 

The Ministry of Commerce has asked the country's exporters of medical products including COVID-19 testing kits, face masks, protective suits, ventilators and infrared thermometers to provide extra documentation when they go through customs clearance, starting from April 1.

The goods seized are the first batch of substandard masks detected by Ningbo airport customs since the new regulations took effect.  

The surgical masks seized by the airport customs authority in Ningbo, home to China's busiest port, had conformity issues in the manufacturers' registration information and goods qualification certificate.

The Ningbo customs authority declined to comment when reached by the Global Times on Wednesday. 

The US is fighting an intense battle against the novel coronavirus pandemic. A total of 731 people died as a result of COVID-19 in New York state from Monday to Tuesday, bringing the state's death toll to 5,489 and marking its deadliest 24 hours since the pandemic took hold there, said Governor Andrew Cuomo on Tuesday.

On April 1, the customs authority in East China's Xiamen city seized a batch of 4,000 KN95 respirators bound for Italy due to a false customs declaration.

The declared brands did not match the actual brands of the products, according to Xiamen customs. 

Similar issues were detected in 48 infrared thermometers bound for Afghanistan on April 2.