Although not aimed solely at China, the new efforts are in part intended to help users circumvent the so-called Great Firewall, a far-reaching menu of direct censorship and “opinion guidance” that restricts what the country’s 450 million Internet users can read or write online.

“The United States continues to help people in oppressive Internet environments get around filters, stay one step ahead of the censors, the hackers and the thugs who beat them up or imprison them for what they say online,” Mrs. Clinton said in the speech, given on Tuesday at George Washington University.

In his comments, the ministry spokesman, Ma Zhaoxu, reiterated China’s oft-repeated contention that Chinese Internet users are unrestrained, with some exceptions “in accordance with the law,” and that China was not opposed to cooperating with other countries that seek to promote a more open Internet. “But we are against any other countries using Internet freedom as a pretext for interfering in others’ internal affairs,” he said.

China has some of the world’s most extensive Internet restrictions, which include blocks on pornographic content and Web sites like Facebook, YouTube and Twitter. Day-to-day censorship, however, is often carried out by privately run Web sites.

Mrs. Clinton’s speech did not get much coverage in China, and censors promptly removed blog posts on the subject sent out by the United States Embassy in Beijing.