(Yicai Global) Feb. 21 -- Wumart Stores, one of China's largest supermarket chains, is allegedly selling out-of-date face masks online that have had their production and expiry dates hidden with labels.

A woman surnamed Wang claims to have recently bought a box of imported N95 face masks through Wumart's e-commerce partner site Dmall, run by Dmall E-Commerce, that expired eight years ago, web portal China Internet Information Centre reported yesterday.

The set of 20 masks, which provide a 95 percent filtering efficiency rate, were imported from the US and cost CNY25 (USD3.55) each. Prices of N95 masks available through online marketplaces range from CNY10 to over CNY100 each.

The production date stamped on the outside of the package was June 2009 and its expiration date was June 2012. However, the Chinese-language label on the bottom of the box covered this information. The retailer did this on purpose, Wang said.

The matter is being looked into and the outlet will give an update soon, the report said, citing members of staff.

This is not the first time that Beijing-based Wumart has raised questions about its mask selling practices. On Feb. 4, it began to promote a package of five South Korean KF94 masks with various assortments of vegetables for the price of CNY199 (USD28).

The bundles, which sold out the same day, were flagged as compulsory consumption. The company responded by saying that customers who did not want to buy all of the bundled products could buy them separately. But the supermarket chain limits the number of protective face masks each shopper can buy a day and masks are only sold over a fixed period each day.

Beijing-based Dmall and Wumart have the same chairman, Zhang Wenzhong, but Dmall's online-to-offline services extend to many large Chinese retailers. The app had over 80 million users as of the end of last year, of which 16 million were monthly active users.

Editor: Kim Taylor