BEIJING — China's top 100 supermarket enterprises maintained growth in online sales last year, data from an industry association showed.

In 2021, online sales of the country's top-100 supermarkets amounted to nearly 100 billion yuan (about 15 billion), up 40 percent year-on-year, according to the China Chain Store and Franchise Association.

The total number of stores owned by these enterprises gained 2.9 percent from a year ago to about 30,000, with 11 firms logging a year-on-year growth of over 5 percent in sales revenue and store numbers.

Due to adverse factors such as COVID-19, the top 100 supermarkets saw declines in customer flow and per-customer transactions last year, said the association.

Their sales narrowed 2.6 percent year-on-year to 907.6 billion yuan in 2021, showed the data.