Chronology of events in US web snooping case

The following is a chronology of key dates in the case.

-- JUNE 2013 --

- 5: British newspaper The Guardian reveals the existence of a secret US court order forcing US telephone company Verizon to provide the National Security Agency with daily information on its customers' calls, from April to July.

- 6: The Washington Post and The Guardian report that the NSA and the FBI have access to servers of major Internet companies such as Microsoft, Yahoo!, Google and Facebook to monitor the web traffic of people outside the United States.

The Internet companies deny they have given the government backdoor access to their servers.

- 7: President Barack Obama says America has to find a balance between privacy and security.

- 9: As US authorities announce the start of an investigation, Snowden, in hiding in Hong Kong since May 20, reveals himself to be the source of the leak.

- 10: Snowden leaves the Hong Kong hotel where he has been staying.

- 12: The European Union toughens its tone with the United States and asks for clarifications regarding the intelligence operation PRISM.

- 15: Facebook and Microsoft reveal that in the second half of 2012 they received thousands of requests from US authorities for information about their customers.

- 17: Apple says it received requests for information from December 2012 to May 2013.

- 18: The NSA director says the surveillance programs helped thwart more than 50 potential terrorist attacks since the September 11 attacks of 2001.

- 21: Snowden is charged with espionage by US authorities, who ask Hong Kong to arrest him.

- 22: The Guardian quotes Snowden as saying Britain is worse than the US when it comes to snooping on telephone conversations.

- 23: Snowden flies to Moscow but does not emerge with other passengers, some of whom suggest he might have been whisked away directly.

According to Russian President Vladimir Putin, Snowden is in the transit zone at Sheremetyevo Airport.

It is revealed the United States has revoked Snowden's passport.

- 24: Snowden does not take the Aeroflot flight from Moscow to Havana he was reportedly checked-in for.

The White House warns that Hong Kong's decision to allow Snowden to leave has harmed efforts to build trust in US-China relations.

- 26: Venezuelan President Nicolas Maduro says Caracas would "almost certainly" grant political asylum to Snowden if he applied for it.

Ecuador denies that it gave Snowden a travel document that allowed him to travel from Hong Kong to Russia.

- 27: Obama says he would not "scramble jets" to intercept any flights carrying Snowden.

- 29: Ecuador President Rafael Correa says he has spoken with US Vice President Joe Biden, and that he asked Ecuador to reject Snowden's asylum request.

- 30: France, Italy and Greece are among 38 "targets" of US intelligence services, according to documents leaked to The Guardian by Snowden.

German weekly Der Spiegel says the European Union was another target of Washington's spy program.

EU, French and German official demand answers from the US.

-- JULY --

- 1: Putin says Snowden is welcome to stay in Russia if he stops leaking intelligence reports and insists "Russia never hands over anybody anywhere."

Snowden accuses the US of "pressuring" the leaders of countries where he was seeking asylum.

Wikileaks reveals he has sent asylum requests to 21 nations.

- 2: Germany, Brazil, Norway, India, Poland, Iceland, Austria, Finland, the Netherlands, Spain -- later followed by France and Italy -- all refuse to grant Snowden asylum.

- 3: A new diplomatic spat erupts after a flight carrying Bolivian President Evo Morales is forced to stop in Vienna, over suspicions he was transporting Snowden.