Edward Snowden: Classified US data shows Hong Kong hacking targets

Classified US government data shown to the South China Morning Post by whistle-blower Edward Snowden has provided a rare insight into the effectiveness of Washington's top-secret global cyberspying programme.

New details about the data can be revealed by the Post after further analysis of information Snowden divulged during an exclusive interview on Wednesday in which the former CIA computer analyst exposed extensive hacking by the US in Hong Kong and the mainland.

The FBI said yesterday it had launched a criminal investigation and was taking "all necessary steps" to prosecute Snowden for exposing secret US surveillance programmes.

FBI Director Robert Mueller told the House Judiciary Committee: "These disclosures have caused significant harm to our nation and to our safety. We are taking all necessary steps to hold the person responsible for these disclosures," he said.

Snowden, the man behind explosive leaks of information on the US government's Prism programme that collected phone and web data from its citizens, has pledged to stay in Hong Kong to fight any attempts by his government to have him extradited.

The detailed records - which cannot be independently verified - show specific dates and the IP addresses of computers in Hong Kong and on the mainland hacked by the National Security Agency over a four-year period.