The Shanghai Municipal Postal Administration on Sunday released a whitelist of 21 enterprises offering postal and express delivery service.

The enterprises include China Post, SF Express, Cainiao, JD Logistics, as well as UPS and FedEx.

"All sorting centers of these major courier brands in the city have resumed operations," read the notice by the administration.

"We'll help the enterprises to further break through the bottlenecks and give full play to the positive role of the industry during this special period," it said.

Government departments and sub-district authorities have also been urged to support such enterprises with their resumption of operations.

The city's postal administration previously said on April 21 that around 10,000 couriers were working in supply transportation and express delivery positions in Shanghai.

Shanghai Observer reported on Monday that over 1,000 couriers with ZTO Express have resumed work.

In addition, more than 500 couriers have resumed work at the Shanghai transit center of STO Express.