Alibaba.com, China's largest e-commerce company, has won approval from the Hong Kong Stock Exchange for a long-anticipated IPO expected to be worth roughly US$1 billion, sources familiar with the deal said.

Alibaba Group, which is partly owned by Yahoo Inc, plans to list its business-to-business operation, Alibaba.com, but does not plan to make its other units part of the initial public offering, one source said.

Jack Ma founded Alibaba in his Hangzhou apartment in 1999 with 18 employees as an online business-to-business marketplace.

Now, Alibaba.com provides a platform for small and medium-sized buyers and suppliers from China and overseas for international and domestic online trading and employs 4,400 full-time staff.

Its marketplaces form a community of more than 24 million members globally.

Alibaba absorbed Yahoo's China business in 2005, and Yahoo bought a 40 percent stake in Alibaba for US$1 billion as part of that deal.

The business-to-business division makes up the largest part of Alibaba Group. Its consumer arm includes the auction firm Taobao, online payments unit Alipay and Yahoo China.

With more than 162 million Web users, China is the world's second-largest Internet market after the United States.

Alibaba, which has long been rumoured as an IPO candidate, has decided to list in Hong Kong instead of the United States.

In 1999 and 2000, Alibaba raised US$25 million from Softbank, Goldman Sachs, Fidelity Investments and other institutions.

Alibaba's IPO is being sponsored by Goldman Sachs and Morgan Stanley, with Rothschild an adviser.