Google promised to step up control of "vulgar" online search results in China late Thursday, after a government-backed arbiter warned that its filtering of pornography was too weak.

"The Google China Web site has not done the work to filter pornographic material in accordance with China's laws and regulations," the China Internet Illegal Information Reporting Center said in a statement on its Web site Thursday.

The criticism follows an official campaign against online smut in China that has led to the shutdown of thousands of Web sites and warnings for many major Internet portals. China also recently demanded that porn filtering software be included with all PCs sold in the country starting next month.

The Chinese statement called for Google to erase all vulgar content and urged China's law enforcement to punish the company.

The center had already found problems with Google's blocking of pornographic search results twice this year, the statement said.

Google said it would strengthen efforts to control the content in a statement on its Chinese blog. The company has always worked to monitor vulgar online content, including content harmful to children, it said.

Google was attacked again later Thursday in news programs broadcast by state-run CCTV that showed Google searches returning links to porn.