WikiLeaks on Monday accused Internet giant Google of handing over the emails and electronic data of its senior staff to the US authorities, and not notifying them for almost three years.

It was acting on warrants that reveal the US Department of Justice investigation into WikiLeaks for leaking hundreds of thousands of classified documents is far broader than it has previously admitted, the whistleblowing site said.

The warrants refer to alleged espionage, theft of US government property, computer fraud and abuse and general conspiracy, which could amount to a jail term of 45 years.

"Today, WikiLeaks' lawyers have written to Google and the US Department of Justice concerning a serious violation of the privacy and journalistic rights of WikiLeaks' staff," the site said in a statement.

WikiLeaks said that Google could and should have challenged the warrants, and also complains that it did not inform those targeted immediately.

The warrants concerned emails, contacts and IP addresses relating to the Google accounts of investigations editor Sarah Harrison, section editor Joseph Farrell and spokesman Kristinn Hrafnsson.

The information was handed over to the US authorities on April 5, 2012, but Google did not inform them until December 23, 2014, according to documents obtained by AFP.

"While WikiLeaks journalists, perhaps uniquely, do not use Google services for internal communications or for communicating with sources, the search warrants nonetheless represent a substantial invasion of their personal privacy and freedom," the organisation added.

- Intelligence target –

WikiLeaks has been targeted by the US authorities since its release in 2010 of 500,000 secret military files on the wars in Afghanistan and Iraq and 250,000 diplomatic cables.

A former army intelligence analyst, Chelsea Manning, is currently serving a 35-year prison term for leaking classified documents to WikiLeaks.

WikiLeaks founder Julian Assange also believes he is a target for prosecution and has been holed up at the Ecuadoran embassy in London since 2012.

He sought asylum there to avoid being sent to Sweden, where he faces allegations of rape and sexual molestation which he strongly denies. He says his extradition to Sweden could see him transferred on to the United States. Google did not response to requests by AFP for comment, but the firm told The Guardian newspaper: "We follow the law like any other company.

"When we receive a subpoena or court order, we check to see if it meets both the letter and the spirit of the law before complying.

"And if it doesn't we can object or ask that the request is narrowed. We have a track record of advocating on behalf of our users."