Christine Assange called on Australians to put pressure on the government to secure guarantees that her son would not be extradited to the United States, fearing for his safety, the Australian Associated Press reported.
"Now Julian's even closer to a US extradition or rendition," Assange told AAP. "It's now up to the (Australian) people to use their democracy or lose it.
"If they don't stand up for Julian, he will go to the US and he will be tortured. And he is the person who stood up for the world to expose the truth."
She said she further feared that her son, if extradited to Sweden, could be held indefinitely without charge and without access to visitors, including lawyers, and that any trial could be conducted behind closed doors.
"People think that because Sweden is a Western country that they have a legal system the same as ours, that's completely untrue," she told AAP.
"From the time he hits Sweden, he is going to be lost to any kind of observation from anybody to understand if his human rights are being breached."
But Petter Asp, a professor of criminal law at Stockholm University, said that claims by Assange's mother were off base.
"That's a clear misunderstanding," he told The Local.
While he acknowledged that Sweden's legal system has certain shortcomings, he said that they were no more severe than shortcomings in any other country governed by the rule of law.
According to Asp, much of the criticism directed at the Swedish legal system is unfounded and that Assange would "definitely" receive a fair trial in Sweden.
"One reason for people questioning the Swedish legal system is that a lot of people have sympathy with what he's done in other parts of his life," said Asp.
"But what is quite clear is that even people who do good things can also do bad things."
Earlier on Wednesday, two judges at the High Court in London rejected arguments by the 40-year-old Australian, whose anti-secrecy website has enraged governments around the world, that his extradition would be unlawful.
Assange said he would consult his lawyers about whether to make a further appeal to England's Supreme Court, but doing so would be difficult as judges must first decide that the case is of special public interest.
While Asp refused to pass judgement on the merits of the case or speculate on how long prosecutors may need to pursue their investigation once Assange lands in Sweden, he didn't expect the extradition order to be reversed.
"I can't see how it would be overturned," he said.
Assange has strongly denied the allegations, claiming they are politically motivated and linked to the activities of WikiLeaks. He has been under virtual house arrest since he was first detained in December.
mother called for Australian Prime Minister Julia Gillard to do more for Assange, who she said had done nothing more than speak the truth.
"Julia Gillard should be standing up to the US and saying 'not this time. You're not going to take one of our countrymen and torture them just because they told the truth'," she told AAP.
"He's been crucified for doing what he was brought up to do," she added.
"I brought my son up to tell the truth, to believe in justice. He was brought up to believe he lived in a democracy and to right any wrongs that he saw... Now I believe that's not true."
Assange now has 14 days to decide whether he will try to take the case to the Supreme Court of England and Wales.
But leave to appeal can only be granted by either the High Court or the Supreme Court, and then only if it there is a point of law of general public importance.