By Louise Saunders

PUBLISHED: 05:26 EST, 17 July 2013 | UPDATED: 06:29 EST, 17 July 2013

He's best-known for portraying fictional detective, Sherlock Holmes.

But Benedict Cumberbatch couldn't be further away from his television alter-ego in a sneak peek from his latest movie project, The Fifth Estate.

In the action-packed drama, the 36-year-old actor takes on the role of controversial WikiLeaks founder, Julian Assange, as he prepares to leak confidential information on the US military's Afghanistan and Iraq operations to the world's media. 

Scroll down for trailer

The Sherlock star is almost unrecognisable in the role, covering his own auburn curls with dramatic long platinum blonde locks to bear an uncanny resemblance to the Australian activist.

Beginning with Assange and his team watching a clip of American soldiers shooting unarmed reporters, Cumberbatch says in a perfect Australian accent: 'Man is least himself when he talks in his own person. But if you give him a mask, he will tell you the truth.

'One moral man, one whistleblower. Someone who will expose the secrets. That man will expose the most powerful of repressive regimes. Courage is contagious.'

 In action-packed scenes, the actor can be seen dodging bullets and rejoicing as his plans begin to take hold, slowly helping both WikiLeaks and Assange himself to achieve international notoriety.

Addressing a conference as he explains his vision, he says: 'This is information the world needs to know. If you want the truth, you should seek it out for yourself. That's what they're afraid of.'

And it would appear Cumberbatch also got involved with a number of somewhat racy scenes, with the star seen unbuttoning his shirt as a woman undressed in front of him.

Despite being personally asked not to take on the role, Cumberbatch has previously declared his support for the work Assange undertook with WikiLeaks.

He told New York Magazine: 'He [Assange] hates the idea of the film and asked me not to do it. No matter how you cut it, he's done us a massive service, to wake us up to the zombielike way we absorb our news.'

The trailer gives a taste of what's to come in the fictional portrayal of how WikiLeaks divulged the White House's classified information to the world.

The upcoming movie, directed by Bill Condon and written by Josh Singer, is partially based on Daniel Domscheit-Berg's book Inside WikiLeaks: My Time With Julian Assange at the World's Most Dangerous Website.

However, WikiLeaks have not given their blessing to the film, with spokesman Kristinn Hrafnsson recently proclaiming: 'If the film reflects what is written in those books, it will provide a negative view of WikiLeaks with limited impartiality.

'Hollywood is not exactly the best reflection of contemporary history. I don’t believe WikiLeaks or Julian has been contacted by Dreamworks, but I don’t expect any courtesy from any organisation within Hollywood.'

Meanwhile, Assange himself slammed the project as a massive propaganda attack on WikiLeaks and the character of my staff'.

The Dreamworks movie also stars Laura Linney, Anthony Mackie and David Thewlis.

It remains to be seen if Assange will still be camping out at the Ecuadorian embassy in London by the time the movie hits cinemas.

In December 2012, the Australian activist made a rare public appearance from the balcony of the embassy.

Marking his six month anniversary within the building, he insisted the 'door is open' for talks to ensure his safe passage to Sweden to challenge allegations of sexual assault - which he denies.

The Australian has since been granted political asylum in Ecuador but has remained inside the embassy as he will be arrested if he steps outside over breaking his bail conditions.

Assange is wanted for questioning in Sweden over the sexual assault allegations, but fears being sent to the United States to be questioned over his whistle-blowing website.

He recently said that the Pentagon claimed the existence of WikiLeaks was an 'ongoing crime'.

He said: 'While that remains the case and while my government will not defend the journalism and publishing of WikiLeaks, I must remain here.

‘However, the door is open, and the door has always been open, for anyone who wishes to use standard procedures to speak to me or guarantee my safe passage.'

The Fifth Estate is scheduled for release on October 11 in the US, before opening in UK cinemas on January 1 2014.