Assange faces arrest by British police on charges of skipping bail and also fears extradition to the US over WikiLeaks' publication of secret US military and diplomatic documents.
Assange said British authorities had refused to confirm or deny if the US had issued a warrant for his extradition from the UK.
Barns, who is part of Assange's legal team, wants Prime Minister Malcolm Turnbull to intervene and speak to Washington and London.
"The Australian Government, which washed its hands of Julian Assange a long time ago, now needs to get involved - this is one of its citizens," he told Sky News yesterday.
Deputy Labor leader Tanya Plibersek said Assange still had questions to answer, but Barns said there were no outstanding issues and he would welcome a call from her.
"This seems to be that element of the Labor party which is in a cabal with Washington and London and refusing to stand up for an Australian citizen," he said.
Appearing on a balcony of the Ecuadorean embassy in London on Friday, Assange told supporters and a large media throng he had been detained and slandered as his children grew up without him.
"That's not something I can forgive, it's not something I can forget," he said. The 45-year-old gave a clenched-fist salute as he welcomed the Swedish decision, hailing it as "an important victory". He said he was prepared to talk to UK and US authorities about his position despite "extremely threatening remarks" being made.
Assange said the claim the UK had the right to arrest him for seeking asylum when no charges had been laid against him was "simply untenable".
Assange looks set to remain in the embassy for a while yet.
For skipping bail in the UK over the Swedish accusations, Assange could face a year in jail.
The UN Working Group on Arbitrary Detention said in 2016 that Assange was in effect being arbitrarily detained in violation of international law.
- AAP
