The United States has been accused of engaging in industrial espionage as well as using mobile phone apps such as Angry Birds to scoop up personal data.

In the latest revelations by whistleblower Edward Snowden, he says the National Intelligence Agency (NSA) spies on big companies that compete with US firms.

During a recorded, six-hour interview with a German TV network at a hotel in Russia, the former NSA contractor said: "There is no question that the US is engaged in economic espionage".

"If there's information at a foreign company that's beneficial to US national interests - even if it has nothing to do with national security - then they'll take that information nevertheless".

The NSA has rejected his claims saying it doesn't "steal trade secrets" on behalf of US companies.

Agencies exploiting leaky 'apps' like Angry Birds

Meanwhile the New York Times reported documents leaked by Snowden show the NSA and Britain's Government Communications Headquarters are tapping into smart phone apps to obtain personal data.

The Angry Birds game has been hugely popular. ( ABC News )

It says classified documents show "leaky" apps such as Google Maps, mobile versions of Facebook and Twitter and the game Angry Birds, among others, are being exploited by the agencies.

Each time someone opens an application, the eavesdropping agencies can vacuum up data that reveals the user's location, age, personal address list and other information, according to the Times.

The NSA has not denied the reports, reiterating that the agency is not out to spy on ordinary people and is respectful of privacy rights.

"The communications of people who are not valid foreign intelligence targets are not of interest to the National Security Agency," spokeswoman Vanee Vines said in a statement.

"Any implication that NSA's foreign intelligence collection is focused on the smartphone or social media communications of everyday Americans is not true," she said.

Snowden tells German TV he sleeps well at night

After leaking explosive details of secret surveillance schemes to newspapers, Snowden fled the US.

He arrived in Russia in June as a fugitive and spent more than a month holed up in a Moscow airport before being granted a year's asylum.

US federal prosecutors have filed a criminal complaint against Snowden, charging him with espionage and felony theft of government property.

His leaks have deeply embarrassed president Barack Obama's administration by revealing the massive scale of America's spying efforts, including on the country's own allies such as German chancellor Angela Merkel.

In the interview with the German TV network, Snowden said he believes there are "significant threats" to his life, but that he sleeps well because his massive leaks about American spying were "the right thing to do".

ABC/AFP