21 June 2013 | BBC

The US justice department has filed criminal charges against a fugitive ex-intelligence analyst who leaked details of a secret surveillance operation.

The charges against ex-National Security Agency (NSA) analyst Edward Snowden include espionage and theft of government property.

In May, Mr Snowden fled to Hong Kong after leaking details of a programme to monitor phone and internet data.

The US is also reported to be preparing an extradition request.

His leaks revealed that US agencies had systematically gathered vast amounts of phone and web data.

The criminal complaint has been lodged with a federal court in an eastern district of Virginia and a provisional arrest warrant had been issued, court documents show.

Mr Snowden, 30, was charged with "Theft of Government Property", "Unauthorized communication of National Defense Information Information" and "Willful Communication of Classified Communications Intelligence".

The BBC's Katy Watson in Washington says the move shows how seriously the administration is taking the issue.

Mr Snowden's leaks led to revelations that the US is systematically seizing vast amounts of phone and web data under an NSA programme known as Prism.

Mr Snowden has also alleged that US intelligence had been hacking into Chinese computer networks.

He said he had decided to speak out after observing "a continuing litany of lies" from senior officials to Congress.

The leaks have been a severe embarrassment for President Barack Obama's administration.

US officials have since launched a robust defence of the practice by US intelligence agencies of gathering telephone and internet data from private users around the world.

They say Prism cannot be used to intentionally target any Americans or anyone in the US, and that it is supervised by judges.

Earlier this week the head of the NSA, Gen Keith Alexander, told Congress that it had helped to thwart terror attacks.