China's largest e-commerce firm Alibaba Group has postponed indefinitely its listing plans for its subsidiaries, said a company source on Thursday.

Alibaba Group, which is 40 percent owned by Yahoo, owns China's largest consumer e-commerce platform Taobao and its largest e-payment system, Alipay.

Alibaba Group's Chairman Jack Ma said an internal email to employees that the subsidiaries are not yet mature enough for initial public offerings, and Alibaba will instead speed up investment on e-commerce infrastructure over the next few years, the China Business News reported on Thursday.

A company source confirmed Ma's email to employees and its content about the postponment of the subsidiaries' listing plans.

A top executive at Taobao had said last week that there were no plans for an initial public offering.

Taobao handled 400 billion yuan ($60.78 billion) in transaction value last year, an Alibaba Group executive said last week.

Taobao is one of Alibaba Group's crown jewels and its valuation is a point of contention between the group and Yahoo. Alibaba Group said last September the company had offered to buyback Yahoo's stake in Alibaba, but the offer was rejected.

The group, which dominates the country's e-commerce industry, announced plans last week to invest up to $4.5 billion over the medium term to build a nationwide warehouse network to boost China's logistics industry. ($1=6.58 Yuan)