WikiLeaks founder Julian Assange has been accused of placing the United States at risk of “serious harm” by publishing thousands of secret and classified documents in new charges in the US.

The charges, under the Espionage Act, are contained in an 18-count indictment announced on Friday morning (Australian time).

The new charges go far beyond an initial indictment against Assange made public last month that accused him of conspiring with former army intelligence analyst Chelsea Manning in a conspiracy to crack a Defence Department computer password.

The new indictment says Assange conspired with Manning to obtain and disclose classified national defence documents, including State Department cables and reports on the wars in Iraq and Afghanistan.

It says his actions, including publishing the names of confidential sources for American armed forces, “risked serious harm” to the US.

US media reports say such a charge under the Espionage Act has never been successfully prosecuted.

Justice Department officials emphasised that Assange’s actions threatened the wellbeing of US operatives by publishing human source names, knowing they could be hurt.

“Julian Assange is no journalist,” Assistant Attorney General John Demers said.

“No responsible actor, journalist or otherwise, would purposely publish the names of individuals he or she knew to be confidential sources, exposing them to the gravest of dangers.”

New charges ‘threaten’ journalists

A lawyer for Assange disputed the Department’s assessment and said the “unprecedented charges” against his client threatened journalists looking to inform the public about the US government’s actions.

His lawyer Barry Pollack said the indictment charged Assange with “encouraging sources to provide him truthful information and for publishing that information.”

Mr 
Pollack said the case posed a threat to journalists doing their job.

Wikileaks said the decision was “madness”.

This is madness. It is the end of national security journalism and the first amendment. https://t.co/wlhsmsenFw

— WikiLeaks (@wikileaks) May 23, 2019

Meanwhile, Manning, who was convicted in a military court for providing a trove of classified documents to WikiLeaks, is currently in a Virginia jail on a civil contempt charge.

Manning spent two months in detention from March after she refused to testify to a grand jury investigating WikiLeaks.

That grand jury is sitting in Alexandria, where Assange is charged. She could remain in jail for up to 18 months, the length of the current grand jury’s term.

Manning has said she believes prosecutors want to question her about the same conduct for which she was convicted at her court-martial.

She served seven years of a 35-year military sentence before receiving a commutation from then-president Barack Obama.

Assange, 47, is currently serving a 50-week prison term in London after being evicted from the Ecuadorian Embassy in April. The US is seeking his extradition.

-with AAP