A major oxygen cylinder supplier in Shanghai has halted operation and remains closed on Monday after employees tested positive for COVID-19.

The Shanghai Shenwei Medical Gas Company, the city's largest residential oxygen cylinder supplier, supplies more than 90 percent of oxygen for home therapy.

“The factory has been offline since April 6. We have transferred part of the remaining inventory after disinfection; however, the inventory is almost run out,” a general manager of the company surnamed Yuan told the Global Times on Monday.

Yuan said that as of Monday all the confirmed cases and their closed contacts were transferred to the centralized isolation centers. The company is working to resume operation following the requirement of government.

“We have been contacting professional institutions for environmental sampling and third-party disinfection. However due to a large disinfection demand in the city the process takes time,” Yuan said.

The pause came after one of the company's employees in charge of filling oxygen cylinders tested positive for coronavirus, leading to a complete suspension of production and disturb in oxygen distribution.

One resident of Shanghai surnamed Zhao, who was affected by the disruption in the supply of residential oxygen, told local media SMG on Sunday that his 70-year-old mother, who has needed round-the-clock oxygen for the past seven years due to a serious illness, would run out of oxygen the next day.

An employee of the oxygen company told SMG on Sunday that local authorities had previously allowed the company to resume production after a complete disinfection. However, the factory was closed again on April 8 without giving further notice when production would resume.

A company official said on Sunday that the factory was sealed for disinfection and was waiting for the environmental monitoring results to be released on Monday.

"There is still a batch of oxygen cylinders that have been filled and are expected to be transferred as soon as possible," added the company official on Sunday, promising that they would do their best to secure the supply of residential oxygen to residents in urgent need.

Company officials said they hope to speed up disinfection and environmental monitoring to ensure oxygen supply to residents who need it. Authorities in the Jiading district of Shanghai, where the company is located, said they are coordinating the matter at full speed.