AliExpress Korea CEO Ray Zhang speaks after signing an agreement with the Fair Trade Commission about voluntary safety checks, in Seoul, May 13. Yonhap

AliExpress and Temu are facing a decline in growth momentum in Korea as consumers voice increasing concerns about the sale of unsafe and low-quality products by the Chinese e-commerce platforms, according to data and industry officials, Tuesday.

Data from market tracker Mobile Index shows the number of monthly active users (MAU) for AliExpress continued to decline in April and May. In March, the figure stood at 6.94 million but dropped to 6.31 million in May, marking a 9 percent decrease. Similarly, Temu's MAU fell by 450,000 to 6.48 million in May compared to the previous month.

The two Chinese online shopping platform operators made aggressive inroads into the Korean market with an ultra-low pricing strategy until the first quarter. However, their momentum quickly waned following significant public backlash over the sale of products containing carcinogenic substances.

An AliExpress customer said he chose not to use the Chinese shopping platform due to safety concerns.

"Just like most other customers, I was also attracted to their ultra-low prices earlier this year," said the customer who wished to be identified only by his surname, Kim. "But after reading reports about them selling such products, I do not use them anymore. My health means a lot more than saving on costs."

Additional data from BC Card, the largest payment processing firm in the nation, indicates that the Chinese e-commerce firms have seen sales decline over the past few months. Combined sales fell by 0.8 percent in May compared to the previous month. The decline was more pronounced in April, with a sharp drop of 40.2 percent from the month before.

An official at a major retail firm attributed this trend to the weakening brand reputation of the Chinese firms.

"Korean shoppers are particularly discerning when purchasing items," the official said. "Even if the Chinese e-commerce players have achieved robust growth through unmatched price competitiveness, this strategy is not sustainable unless their products meet strict standards expected by local customers. Any involvement in controversies seriously damages their brand image."

However, the official also acknowledged that AliExpress and Temu remain significant threats to Korean rivals, as they are actively addressing their weaknesses by increasing investments in the local market. AliExpress, for instance, recently announced plans to invest $1.1 billion (approximately 1.52 trillion won) over the next three years to establish a logistics center and enhance customer protection measures.

The investment was intended to address the inconveniences caused by slow delivery services. Chinese firms struggle to match the fast delivery times of local counterparts like Coupang. According to a recent survey by the Korea Chamber of Commerce and Industry, over 80 percent of 800 customers reported experiencing inconvenience and dissatisfaction with Chinese shopping platforms, citing issues such as delivery delays and poor product quality.