US Secretary of State Hillary Clinton has urged Beijing to investigate cyber-attacks that recently led the internet company Google to threaten to pull out of China.
Ms Clinton says companies such as Google should refuse to support politically-motivated internet censorship.
"We look to Chinese authorities to conduct a thorough review of the cyber intrusions," she said.
"We also look for that investigation and its results to be transparent."
China says the row with Google should not be linked to relations with the US.
Google said on 12 January hackers had tried to infiltrate its software coding and the email accounts of Chinese human rights activists, the BBC reports.
The California-based company, which launched in China in 2006, said it would quit the country unless the government relaxed censorship.