Beatrice Ask's comments to The Associated Press reveal the irritation among senior Swedish officials at the arguments used by Assange's lawyers in fighting his extradition in a British court, where closing arguments are set for Friday.
The lawyers defending Assange, who is accused of sexual misconduct against two Swedish women, say a closed-door trial in Sweden would represent "a flagrant denial of justice."
They also say he risks being handed over to the United States, which is investigating whether Assange's secret-spilling website should be held responsible for leaking classified information.
Assange "has a lot of prejudice," Ask said in an interview at the Swedish Parliament. "I think it's beyond doubt that we are very careful about the independence and quality of the justice system in this country.
"Everyone is equal before the law. He is suspected, accused of a serious crime and should of course present himself for interrogation," she said.
WikiLeaks has angered the U.S. and other governments by publishing tens of thousands of secret military documents on the wars in Afghanistan and Iraq as well as a massive trove of U.S. diplomatic cables.
Assange's supporters say the rape allegations are trumped up and possibly politically motivated, charges that the women's lawyer has denied.
Leaked police documents show one of Assange's accusers claims he initiated sex with her while she was sleeping, which can be considered rape under Swedish law. The other claims he intentionally damaged a condom and pinned her down while having consensual sex. Assange denies wrongdoing.
He met both women in connection with a seminar on free speech in Stockholm in August.
Assange's objections to the extradition range from how the arrest warrant was issued to the "secret" nature of rape trials in Sweden, where such hearings are often held behind closed doors out of respect for the victims.
"You cannot have a fair trial when the press and the public are excluded from the court," lead defense lawyer Geoffrey Robertson said Tuesday. That's especially relevant for someone like Assange, who has faced "vilification" worldwide, Robertson said.
The defense also produced witnesses to attack the conduct of prosecutor Marianne Ny, including a retired Swedish judge who described Ny as having "a rather biased view against men."
Those comments prompted Sweden's top prosecutor to issue a statement defending Ny's competence and her handling of the case.
Even Prime Minister Fredrik Reinfeldt weighed in, saying everyone who lives in Sweden knows its justice system is "well-functioning."
Both Reinfeldt and Ask dismissed suggestions by Assange's supporters that the sex allegations are part of a politically motivated conspiracy.
"That's taken out of thin air. We don't have that influence and should not have that influence on the judiciary," Ask told the AP.
Sweden is well-respected internationally for its democratic and egalitarian society. Transparency International ranks Sweden as one of the least corrupt countries in the world.
Still, even Swedish experts concede there are problems with how the Assange case has been conducted. For example, prosecutors released his name to the media just hours after the investigation was launched.
That is highly unusual and prosecutors have struggled to explain it. At one point they claimed they didn't release the name; they just confirmed it to a newspaper that already had it.
Another issue is why they didn't interrogate Assange about the rape allegation earlier. He was questioned on Aug. 30 - 10 days after the investigation started - but only about a less serious allegation of harassment.
On the streets of Stockholm, people have mixed feelings about the case.
Karl-Henrik Posse, a 65-year-old horse farmer, said he trusts the Swedish courts will give Assange due process. "We won't put him behind bars if he is innocent," Posse said.
Fashion merchandizer Carolina Neckelius, 25, wasn't so sure.
"I don't think he will get a fair trial here," she said. "It seems like everyone is against him because of this website so whatever he does, they will be against him."
Nils Rekke, head of the legal department at the prosecutor's office in Stockholm, said he views the criticism against his country's justice system as "a tactic from the defense."
He chuckled at the fact that some of Assange's supporters have used the term "Banana Republic" to describe Sweden - a Scandinavian constitutional monarchy.
"Of course that is wrong: both republic and banana," Rekke said.
Associated Press writers Malin Rising in Stockholm and Jill Lawless in London contributed to this report.