China has expressed "grave concern" over former U.S. spy agency contractor Edward Snowden's allegations that the United States had hacked into computers in China, saying it had taken up the issue with Washington.
A statement issued late on Sunday by China's foreign ministry came a day after Hong Kong's South China Morning Post newspaper quoted Snowden offering new details about U.S. surveillance activities. These included accusations of U.S. hacking of Chinese mobile phone firms and targeting of China's Tsinghua University.
Snowden flew from Hong Kong to Moscow on Sunday and was seeking asyulum in Ecuador.
"We express grave concern about the recent disclosures of the U.S. government's cyber attacks on China," Foreign Ministry spokeswoman Hua Chunying said in the statement. "This once again proves that China is a victim of cyber attacks."
Hua said China has "made representations to the United States".
Cyber security is a major irritant between China and the United States and was one of the main topics on the agenda at the first summit between President Xi Jinping and President Barack Obama, held earlier this month.
Hua reiterated China's stance that the country "opposes all forms of cyber attacks".
"We are willing to work with the international community to strengthen dialogue and cooperation and safeguard peace and stability in cyberspace," Hua said.