A group of almost 200 prominent names have appealed to Prime Minister Julia Gillard to defend WikiLeaks founder Julian Assange.

Many prominent US figures have called for Mr Assange's death since his whistleblower organisation began releasing hundreds of US diplomatic cables last month.

And Ms Gillard has been accused by Mr Assange's lawyers of prejudicing any case against him by claiming he is "guilty of illegality" for leaking the documents.

But in the open letter posted on the ABC's Drum website, figures such as writer Noam Chomsky, former Family Court chief justice Alastair Nicholson, retired intelligence officer Lance Collins and actor Max Gillies call on Ms Gillard to ensure Mr Assange's safety in light of the inflammatory rhetoric surrounding WikiLeaks.

"We therefore call upon you to condemn, on behalf of the Australian Government, calls for physical harm to be inflicted upon Mr Assange and to state publicly that you will ensure Mr Assange receives the rights and protections to which he is entitled, irrespective of whether the unlawful threats against him come from individuals or states," they write.

In the letter, almost 200 signatories including Chaser star Julian Morrow, Greens MP Adam Bandt and author Helen Garner, say the Prime Minister needs to make a strong statement in support of freedom of information and resist calls to punish Mr Assange for the leaks.

"We urge you to confirm publicly Australia's commitment to freedom of political communication; to refrain from cancelling Mr Assange's passport, in the absence of clear proof that such a step is warranted; to provide assistance and advocacy to Mr Assange; and do everything in your power to ensure that any legal proceedings taken against him comply fully with the principles of law and procedural fairness," the letter states.

"A statement by you to this effect should not be controversial - it is a simple commitment to democratic principles and the rule of law."

It says the leaks represent a "watershed" in the cause of freedom of speech, and the Government can make a difference by speaking out in defence of Mr Assange.

"In many parts of the globe, death threats routinely silence those who would publish or disseminate controversial material," it writes.

"If these incitements to violence against Mr Assange, a recipient of Amnesty International's Media Award, are allowed to stand, a disturbing new precedent will have been established in the English-speaking world."

Mr Assange has become the focal point for anger over the latest leaks, which detail private cables of US diplomats and have revealed damaging and embarrassing information about senior government figures around the world.