Lawyers for WikiLeaks publisher Julian Assange have filed an appeal against his extradition to the United States, and the UN human rights chief supported the Australian, writes The Guardian.

Assange, 51, has been charged in the United States on 17 charges of espionage and one charge of computer misuse in connection with WikiLeaks' release of thousands of military and diplomatic documents. The charges carry a maximum penalty of 175 years in prison.

WikiLeaks reports that Assange's legal team has filed perfect grounds of appeal with the UK High Court against the US and UK Home Secretary Priti Patel, which approved his extradition in June.

Assange's lawyers say he is being persecuted and punished for his political views.

Assange remains in London's Belmarsh Prison, where he has been in detention since April 2019.

Last year, a UK judge blocked his extradition, but the US government successfully appealed to the High Court. Assange recently suffered a mini-stroke.