SAN FRANCISCO. Google’s threat to quit China over censorship and hacking intensified Sino-U.S. frictions yesterday as Washington, D.C., said Internet control was a serious issue and demanded an explanation from Beijing.

 

Beijing has not made any significant comment since Google, the world’s top search engine, said it will not abide by censorship and may shut its Chinese-language google.cn Web site because of attacks from China on dissidents using its Gmail service and on companies.