State-owned telecom company China Unicom confirmed that the government had ordered the block, the Financial Times reported, citing a source. Microsoft didn't immediately respond to a request for comment but is reportedly investigating the matter.
If Bing is indeed blocked in China, it would become the second major search engine to exit the country. Google withdrew its search engine and other websites in 2010 to avoid censorship and any compromise to its commitment to a free and open internet.
Facebook, Twitter and Yahoo are among the thousands of websites originating in the west that are blocked by the so-called Great Firewall of China.