Alibaba.com, China mainland's biggest online marketplace, plans to set up a branch in Japan this year as part of its strategy to promote its brand outside the mainland.

Also on the expansion list are the United States and European markets, the origins of most overseas orders.

"Our emphasis will be to develop overseas buyers and help Chinese mainland suppliers explore the international market and attract more buyers from Europe, U.S. and Japan," said an official with Alibaba.com Corp, who asked not to be named.

The Website provides a cyber hub for millions of mainland suppliers that are seeking to export their goods.

Hangzhou-based Alibaba.com Corp, operator of Yahoo China, auction site Taobao.com and online payment tool Alipay.com, already has offices in Hong Kong, Europe and America for its B2B business, though most are small.

The company ranks No.1 in mainland's online B2B market, holding a share of nearly 70 percent in the fourth quarter last year, according to Analysys International, a Beijing-based consulting firm.

There are more than 20 million registered business users, mostly small and medium mainland companies, on its B2B site, including several millions of overseas buyers.

Other mainland Internet firms also are expanding beyond the country's borders.

Baidu.com, mainland's most used search engine, launched its first overseas site in Japan last week, with an initial investment of 15 million U.S. dollars.