The US government is hacking Chinese mobile phone companies to steal millions of text messages, Edward Snowden has told the South China Morning Post . And the former National Security Agency contractor claims he has the evidence to prove it. The former CIA technician and NSA contractor, hiding in Hong Kong after the US sought his arrest, made the claims after revealing to the Post that the NSA had snooped on targets in Hong Kong and on the mainland. “There’s far more than this,” Snowden said in an interview on June 12. “The NSA does all kinds of things like hack Chinese cell phone companies to steal all of your SMS data.” Text messaging is the most preferred communication tool in mainland China, used widely by ordinary people and government officials from formal work exchanges to small chats. Government data show that the Chinese exchanged almost 900 billion text messages in 2012 , up 2.1 per cent from the year before. China Mobile is the world’s largest mobile network carrier, with 735 million subscribers by the end of May. China Unicom, the second largest, has 258 million users. China Telecom comes in third with 172 million users. Snowden’s leaks have rocked the international community for the past two weeks and fired up a debate about US government surveillance of citizens’ phone calls and internet browsing data without due cause. For years, cybersecurity experts on the mainland have been concerned that telecommunications equipment was vulnerable to so-called “backdoor” attacks, taking advantage of foreign-made components. They have kept quiet because domestic hardware suppliers were still striving to catch up with their international competitors. The NSA does all kinds of things like hack Chinese cell phone companies to steal all of your SMS data. Edward Snowden Now, as the likes of Huawei, Datang and ZTE dramatically improve their suite of products and the reliance on foreign-made parts has dropped, some experts with ties to Beijing have become more vocal. Fang Binxing, president at the Beijing University of Posts and Telecommunications and widely believed to be the father of China’s “great firewall”, which restricts access to the web, told News China in October last year that foreign equipment was a serious threat to national security. “China should set up a national information security review commission as soon as possible,” he said. Telecom companies have started replacing foreign-made equipment. China Unicom quietly replaced all Cisco routers at a key backbone hub in Wuxi, Jiangsu last year, according to the National Business Daily. The changes are being kept quiet to avoid panic and embarrassment to the government, people in the industry say. A series of reports based on documents provided by Snowden to The Guardian revealed how the US compelled telecommunications provider Verizon to hand over information about phone calls made by US citizens. The leaked documents also revealed the Prism programme, which gave the US far-reaching access to internet browsing data from Google, Facebook, Apple, Skype, Yahoo and others. The US and UK also had technology which gave them unauthorised access to Blackberry phones of delegates at two G20 summits in London in 2009, Snowden said. The US government has defended its electronic surveillance programmes during congressional hearings with claims that up to 50 would-be terrorist attacks were foiled because of the intelligence gathered by the NSA. US President Barack Obama says the NSA is not listening in on phone calls or reading emails unless legal requirements have been satisfied.