NSA leaks journalist Glenn Greenwald will leave the Guardian newspaper

Glenn Greenwald announced he would be leaving the paper on Tuesday evening to pursue 'a momentous new venture'

Glenn Greenwald, the journalist who broke allegations about the National Security Agency by whistleblower Edward Snowden has announced he is quitting the Guardian newspaper to pursue a "dream journalistic opportunity". (AFP)

The journalist who broke allegations by whistleblower Edward Snowden over the National Security Agency has announced he is quitting The Guardian newspaper to pursue a "dream journalistic opportunity".

Glenn Greenwald announced he would be leaving the paper on Tuesday evening, having worked with The Guardian since August 2012. Over the past year, Mr Greenwald has broke a string of stories concerning surveillance by the NSA based on files leaked by Mr Snowden, a former contractor for the agency who has now claimed asylum in Russia.

In a statement posted on his blog, Mr Greenwald said: “My partnership with The Guardian has been extremely fruitful and fulfilling: I have high regard for the editors and journalists with whom I worked and am incredibly proud of what we achieved.

“The decision to leave was not an easy one, but I was presented with a once-in-a-career dream journalistic opportunity that no journalist could possibly decline.”

Mr Greenwald began his career as a constitutional and civil rights lawyer and went on to become a journalist and political commentator.

He said he is leaving to pursue "a momentous new venture" but was unable to provide details as news of his departure had leaked prematurely, but said it will be "unveiled very shortly".

However, he told online news site Buzzfeed his new venture would be a "very well-funded... very substantial new media outlet".

“My role, aside from reporting and writing for it, is to create the entire journalism unit from the ground up by recruiting the journalists and editors who share the same journalistic ethos and shaping the whole thing — but especially the political journalism part — in the image of the journalism I respect most,” said Greenwald.

Sources speaking to Reuters have suggested that the venture is being funded by eBay founder and philanthropist Pierre Omidyar.

Omidyar, 46, became a billionaire at the age of 31 following the 1998 IPO of eBay, with Forbes currently estimating his net worth as $8.5 billion. He has been involved in online investigative journalism since the 2010 launch of Honolulu Civil Beat, a website covering civic affairs in Hawaii. In September 2013 the site partnered with The Huffington Post to launch the HuffPost Hawaii.

A spokesperson for The Guardian said they were disappointed to be losing Greenwald but understood "the attraction of the new role he has been offered".

“Glenn Greenwald is a remarkable journalist and it has been fantastic working with him. Our work together over the past year has demonstrated the crucial role that responsible investigative journalism can play in holding those in power to account.

“We wish him all the best.”