Australia says it will oppose the death penalty for Julian Assange if he's extradited to the United States, as protesters in Sydney called for his release and Australia's journalists' union voiced support for him.

The Australian Wikileaks founder was arrested Thursday in London's Ecuadorian Embassy and the judge found him guilty of breaching his bail conditions. He faces a U.S. charge of conspiring to reveal government secrets.

While Prime Minister Scott Morrison says any extradition plans have "nothing to do with Australia," Foreign Minister Marise Payne has responded to fears from Assange's supporters over his possible punishment in the U.S., saying Australia is "completely opposed to the death penalty."

About 30 people marched in Sydney to support Assange and Australia's journalists' union says he's being pursued for acts of journalism.