Edward Snowden to make virtual return to Hong Kong for top-secret investor conference speech

US intelligence whistleblower Edward Snowden, whose flight to Hong Kong put the city in the global spotlight two years ago, is making another appearance in the city - but not in person.

The National Security Agency operative-turned-fugitive will be a key speaker at the CLSA Investors' Forum from September 14 to 18, addressing the invitation-only audience via satellite from his bolthole in Moscow. Such is the secrecy surrounding the event that the exact time and date of Snowden's online appearance at the Grand Hyatt in Wan Chai has not been confirmed.

Other speakers for the forum - which will be open only to selected clients of the financial services firm - will include Hollywood actor Nicolas Cage, one of the stars of Oliver Stone's forthcoming film Snowden.

Former European Central Bank president Jean-Claude Trichet will also address the forum which, in the past, has attracted speakers as diverse as movie heart-throb George Clooney and failed US vice-presidential candidate Sarah Palin.

While the subject of Snowden's presentation has yet to be announced, CLSA dropped a hint by mentioning that he had recently been working on "methods of enforcing human rights through the application and development of new technologies".

In 2013, Snowden shocked the world by revealing the NSA had been collecting private records on billions of individuals who had not been suspected of any wrongdoing, resulting in the most significant reforms to US surveillance policy since 1978.