Nasdaq-listed Costco reported sales of more than US$110 billion for the year to August.

The American company was tapping into China's vast retail market through the online store without the need for physical operations there, reducing business risk to "nearly zero", said Liu Xingliang, the chairman of Hongmai Software, a Beijing-based internet data analysis company.

Liu said food and health-care products were a good fit because food safety was a big concern in China and consumers had more confidence in foreign brands.

He said the move was also good news for Chinese consumers. "Chinese people always ask friends to buy them clothes and milk powder from abroad because there is no easy channel to access foreign brands," he said.

Alibaba's chief operating officer, Daniel Zhang Yong, said the partnership with Costco would give Chinese consumers a better shopping experience and "will enable us to better support the expansion of cross-border retail sales of consumer goods into China".

Ricky Lai, an analyst at Guotai Junan International, said Tmall was the fast track for a foreign brand to reach the vast Chinese market because Alibaba had already gathered millions of users on its platform.

The e-commerce giant also had a well-managed logistics network and could guarantee fast delivery of purchases.

Launched in February, Tmall Global enables foreign companies to directly advertise and sell to Chinese consumers.

Costco executive vice-president Jim Murphy said it saw tremendous growth opportunities in China "especially in light of Chinese consumers' increasing appetite for imported products".

Costco's online store would offer a range of products including food and health-care products at "highly competitive prices" including its private label Kirkland Signature products, the company said, "addressing the increasing demand for foreign brands by Chinese consumers".

It said there would be no membership requirement for online buyers in China.