WikiLeaks' founder Julian Assange, who is battling extradition from Britain to the United States where he is wanted on criminal charges, has submitted an appeal to the European Court of Human Rights (ECHR), the court confirmed on Friday.

Assange, 51, is wanted by U.S. authorities on 18 counts, including one under a spying act, relating to WikiLeaks' release of vast troves of confidential U.S. military records and diplomatic cables which Washington said had put lives in danger.

Britain has given the go-ahead for his extradition, but he has launched an appeal at London's High Court, with the first hearing expected early next year.

His legal team have also launched a case against Britain at the ECHR, which could potentially order the extradition to be blocked.

"We confirm that an application has been received," a statement from the court said.

Stella Assange, his wife, said she hoped the ECHR would not be needed to consider the case and that it could be resolved in Britain. If the case was taken to the ECHR, she said it "would be a sad day and a major disappointment."

The case has gained prominence this week with major media outlets that had originally worked with Assange over the leaked material writing an open letter to say his prosecution should end.

Meanwhile, Australian Prime Minister Anthony Albanese said he had raised the issue of Assange's release with U.S. officials, saying the matter should be brought to a close.

(Cover: A protestor holds up a sign outside the U.S. Department of Justice during a Free Assange protest in Washington, D.C., October 8, 2022. /CFP)