BEIJING - Google Inc may face a new challenge in China as Microsoft Corp, its main rival in the United States, and Baidu Inc, China's biggest search engine, are joining forces against it in the world's largest Internet market.

Microsoft will provide English-language results from its Bing search engine on Baidu "within this year", the two companies said in a news release on Monday.

The announcement comes at a time that Google's market share in China is falling and Baidu is trying turn that to its advantage to dominate the country's search market.

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Zhang Dongchen, Baidu assistant president, said about 10 million English-language searches are made on Baidu every day, mainly by professionals and university students in China.

By cooperating with Microsoft, he said the two companies can provide "the best search experience" for users.

Marsha Wang, spokeswoman for Google China, declined to comment.

While Baidu dominates online searches in China, it has long lagged behind Google in English-language searches.

The cooperation with Microsoft may help it make up for this and complicate Google's development in China, analysts said.

"It will strengthen Baidu's position in the search market in China and for Microsoft, Baidu's large traffic also provides a platform for it to promote itself, which will help it to gain more users," said Dong Xu, an analyst with domestic research company Analysys International.

Chinese users account for only 8.6 percent of Bing's total users globally, according to the researcher, and Bing is still a tiny player in online searches in China. By contrast, it accounted for 14.1 percent of the US search market in May, following Google's 65.5 percent and Yahoo's 15.9 percent, said website measurement company comScore.

However, it is not known the extent to which the cooperation between the two will affect Google's performance in China.

"It remains to be seen how much English-language searches account for the total Baidu search inquiries and how many Google users will eventually switch to Baidu," said You Tianyu, an analyst with the Chinese research and consultancy company iResearch.

Google's market share reached its peak in China at 35.9 percent in the fourth quarter of 2009, while Baidu registered 58.8 percent at that time.

However, the US search engine controlled 19.2 percent of the market over the first quarter of this year, while Baidu jumped to 75.8 percent, according to Analysys International.

Zhang from Baidu added that the exploration of English-language searches will "largely help Baidu to expand into the overseas search market".