A Chinese Internet information body on Monday said an investigation spanning several months has confirmed "the existence of snooping activities directed against China" as exposed by former National Security Agency (NSA) contractor Edward Snowden. A report by China's Internet Media Research Center said Chinese authorities have looked into the NSA's secret surveillance program codenamed PRISM, which is revealed by British, U.S. and Hong Kong media based on documents leaked by Snowden. "Subsequently, an investigation carried out by various Chinese government departments over several months confirmed the existence of snooping activities directed against China," the report said. Calling China "a main target" of U.S. secret surveillance, the report said Washington has eavesdropped on Chinese state leaders, scientific institutes, universities and enterprises. Documents revealed by Snowden to Der Spiegel showed that the U.S. has conducted mass cyber-attacks on China, targeting Chinese state leaders and Huawei, the second largest telecom solutions provider in the world, it said. Attacks were also aimed at the Ministry of Commerce, the Ministry of Foreign Affairs, as well as Chinese banks and telecommunication companies. According to Der Spiegel, the spying operations also covered several former Chinese state leaders, and government departments and banks. According to a report in Foreign Policy magazine, the United States has stolen a huge amount of important intelligence information from China and other countries via cyber-attacks carried out by the NSA' s Office of Tailored Access Operations (TAO), which was established in 1997. Citing an interview with Snowden in the South China Morning Post (SCMP), the report said the NSA uses numerous methods to hack Chinese telecommunication companies in order to steal the text messages of their users. Snowden also told the SCMP that the NSA had hacked the servers of Tsinghua University, China's most prestigious university. At least 63 computers and servers were attacked in January, 2013. The SCMP report noted that the attack on Tsinghua University, home to one of six main network backbones -- the China Education and Research Network -- means that data from millions of Chinese citizens may have been stolen. The U.S. even retrieves information from computer games and targets chat software for spy operations, the report said. U.S. spying operations have also gathered a huge number of internal emails between staff members of Huawei, including senior executives, since January, 2009. A report on the website of the New York Times said the intelligence operation against China by the NSA is not limited to Huawei. Documents leaked by Snowden in April 2013 revealed that the NSA infiltrated two major Chinese mobile network companies in order to track strategically important Chinese military units.