China will beef up its security following a report that the massive US National Security Agency surveillance of world leaders and civilians has spread into major Chinese cities, a Foreign Ministry spokeswoman said on Wednesday.
According to German magazine Der Spiegel, China has become another victimized country of Washington's monitoring sweep.
US intelligence has been operating a global network of 80 special collection services, including "listening posts" in cities such as Beijing, Shanghai, Chengdu, Hong Kong and Taipei, Der Spiegel said.
Calling cybersecurity "a matter of sovereignty", spokeswoman Hua Chunying said Beijing will take the necessary measures to safeguard its information security.
"We have been concerned about the continuing exposure of the US surveillance activities and will keep a close watch on further developments," Hua said.
Li Haidong, a researcher of American studies at China Foreign Affairs University, said the listening posts in major Chinese cities infringe on citizens' privacy as well as political and economic security.
"Instead of seeking communication and cooperation on cybersecurity, the US further fuels suspicion and distrust between the two countries through these eavesdropping activities," Li said.
Days earlier, Japanese media revealed that the NSA approached the Japanese government in 2011 seeking permission to tap the international fiber-optic cables that traverse the country and carry much of the traffic across East Asia in an attempt to gather more information on China.
Shi Yinhong, a senior expert on US studies at Renmin University of China, said it is not news that the US flaunts itself as a "defender of the law" and constantly points fingers at other countries, including China.
"Yet, the exposed phone tapping violated its domestic and international laws, stained its moral image and invited resentment from its traditional allies," Shi said.
"Maybe Washington has obtained some important information, but it also brings irreparable loss to its diplomacy," he added.
Recent reports, based on documents disclosed by former National Security Agency whistle-blower Edward Snowden, said US spies are responsible for broad monitoring of the communications of 35 world leaders, including German Chancellor Angela Merkel, and millions of foreign civilians.
In June, Snowden revealed that the US government had been hacking into computers in Hong Kong and on the mainland for years through the PRISM programme.
Snowden believed there had been more than 61,000 NSA hacking operations globally, with hundreds of targets such as universities, public officials, business and students, in Hong Kong and on the mainland.
Li said the NSA's extensive surveillance activities regardless of friends and foes reflect its "desperation" to secure its global supremacy and the damage caused has prompted the world to question the legitimacy of the US leadership.
Since last week, countries that fell victim to Washington's eavesdropping in Europe and Latin America have spent days angrily protesting.
Germany and Brazil have drafted a UN General Assembly resolution condemning "indiscriminate" and "extra-territorial" surveillance. The draft has enlisted 19 other countries, including Mexico and France.
However, other experts said that the acrimonious tones of European leaders are political stunts rather than real anger, considering European states have their own spying agenda in the United States.
"A malcontent Europe demands explanations and a termination of the eavesdropping from the United States, without swearing to take retaliatory measures, while Washington, though unapologetic, is working to appease the current spat and pacify its allies," said Jia Chunyang, a researcher of American studies with the China Institute of Contemporary International Relations.
"The eavesdropping scandal may have upset the European media and public, but it can only counts as a 'tactical issue' within the US-EU relations. Their basis for collaboration is not subverted," Jia said. "The two sides will continue deep cooperation on issues such as Syria, Iran and anti-terrorism."
Li said binding international regulations on transnational spying through cyberspace should be put in place to restrict state behaviour.
"The timing and atmosphere is mature for the international society to forge related rules," Li said. "China has already been contributing to that effort."
Reuters and AFP contributed to this story.