George Brandis says Julian Assange should be "man enough" to face sexual assault claims against him.

Julian Assange has hit back at Attorney General George Brandis for saying the Wikileaks founder should be "man enough" to face Swedish sexual assault allegations.

A Swedish court on Wednesday upheld an arrest warrant against Assange. The warrant was issued in 2010 over allegations of rape and sexual molestation which Assange has denied.

The court's decision is another setback for the 43-year-old Australian, who has been holed up at the Ecuadorian embassy in London for more than two years in a bid to avoid extradition to Sweden.

Assange says he fears that if he goes to Sweden he will be extradited on to the United States to face charges for publishing classified material.

But Senator Brandis says Assange should face the claims.

"I think Mr Assange should be man enough to face the allegations against him of being a sexual predator," he told ABC radio on Thursday.

Assange says Senator Brandis had merely stolen comments US Secretary of State John Kerry made about intelligence whistleblower Edward Snowden.

"AG Brandis should stop plagiarising sexist claptrap and start doing his job: defending the legal rights of all Australians," Assange said in a statement to AAP, sent by his Australian lawyer Greg Barns.

Courage is not the sole preserve of men, Assange said.

"WikiLeaks' female staff members, who squared off with a superpower over our work and brought Edward Snowden to safety during the largest intelligence manhunt the world has ever seen, have more genuine courage in their little toes than the entire Abbott cabinet."