WikiLeaks founder Julian Assange expects he will be indicted in the US for espionage and said there were “serious attempts” to take down both WikiLeaks as an organisation and himself as an individual.

Assange was released on bail yesterday ahead of proceedings next week in which Sweden will attempt to extradite him for trial over sex crimes allegations.

Arriving at the Sussex mansion given as his bail address, Assange told reporters that his legal team had heard the US would be taking legal action against him. The espionage charges are expected to be related to the thousands of American embassy cables revealed on WikiLeaks.

Assange told Sky News: “We have heard today from one of my US lawyers that there may be a US indictment for espionage for me coming from a secret grand jury investigation.”

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The WikiLeaks boss said that although this was yet to be confirmed, he was taking the matter extremely seriously.

“One of the concerns that we have had since I have been in the UK is whether the extradition proceeding to Sweden is actually an attempt to get me into a jurisdiction which will then make it easier to extradite me to the United States,” Assange said.

US officials have made no comment on whether it will be charging Julian Assange with espionage. A spokeswoman from the US Department of Justice would said there is ”an ongoing investigation into the WikiLeaks matter”.

Assange is currently wanted in Sweden for alleged sex offences, charges which he denies and has dismissed as a “smear campaign”. His lawyers have accused Sweden of carrying out a “vendetta”.

However the WikiLeaks boss said that clearing his name was secondary to the mission of publishing yet more unseen documents.

“Clearing my name is not the highest work I have. Continuing my work is the highest work I have,” Assange said.