BARCELONA - Chinese fast-fashion retailer Shein plans to become more focused on sustainability, Executive Vice Chairman Donald Tang said on Tuesday, adding that consumers are no longer just concerned about affordability.

Shein sells $10 dresses and $5 tops and has taken market share from other affordable fashion retailers. The company produces clothing in China to sell online in the United States, Europe and Asia and has been criticised for promoting throwaway fashion.

"Consumers these days are no longer looking just at price: in the next phase to continue to grow you need to have ESG in mind," Tang said at the World Retail Congress in Barcelona.

ESG, an acronym for environmental, social, and governance, is a term used to describe corporations' efforts to be more responsible.

Tang said that Shein is offering customers an option to pick higher-quality materials and pay a premium for them for certain items.

He also mentioned Shein Exchange, the company's platform where shoppers can resell used clothes, which launched in the U.S. in October and aims to start in other markets this year.

Shein continues to grow "very robustly", Tang said, and regularly has less than 2% of unsold inventory.

(Reporting by Helen Reid and Corina Pons Editing by David Goodman and Sharon Singleton)