LONDON — Attorneys for WikiLeaks founder Julian Assange launched a blistering attack on the credibility of Swedish prosecutors and two women accusing the 39-year Australian of sexual assault, arguing on day one of an extradition hearing that he faces the prospect of a closed-door show trial if British authorities send him to Stockholm.

Assange, who is wanted for questioning on allegations of sexual molestation, unlawful coercion and rape, appeared calm as he scribbled notes throughout the first half of the two-day hearing in a southeast London courtroom. The hearing is to determine whether British authorities will agree to honor a Swedish warrant for Assange, who is under partial house arrest in Britain as he fights extradition.

The warrant hinges on allegations by two Swedish women with whom Assange had brief affairs in Stockholm in August 2010. Both claim that specific encounters with Assange became nonconsensual, with one saying he engaged in unwanted, unprotected sex with her while she was asleep, an act considered criminal rape in Sweden.

Geoffrey Robertson, one of Assange’s lead attorneys, argued that the alleged acts would not be considered crimes in Britain and thus were not extraditable offenses. He called to the stand a former Swedish judge, Brita Sundberg-Weitman, who described Marianne Ny, the Swedish prosecutor seeking Assange’s arrest, as an over-zealous women’s rights crusader with a bias against men.

“I think she is so preoccupied with the situation of battered women and raped women that she has lost balance,” Sundberg-Weitman said of Ny. Crown prosecutors representing their Swedish peers rejected the assertions about Ny.

Robertson also criticized Swedish prosecutors for their apparent readiness to file serious criminal charges against Assange while he is still only wanted for questioning and added that rape proceedings in Sweden are conducted in private, posing the risk of “a flagrant denial of justice.”

Clare Montgomery, a prosecuting attorney, rejected defense assertions that Sweden was in collusion to hand Assange over to the United States if U.S. officials file charges against him associated with the disclosures of secret documents on the Internet.

In comments in the court, and in witness testimony by a blogger who claimed one of the women had deleted a light-hearted tweet about Assange posted after an alleged act of sexual assault, the defense sought to paint his accusers as jilted lovers out for revenge.

But Montgomery sought to bring home the seriousness of the allegations, graphically describing the account of one of the women who said she had protested the continuation of sex after a condom broke.

Before heading back to the rural Georgian mansion to which he is partially confined for the length of the legal proceedings, Assange took to a microphone outside the courthouse to again proclaim his innocence, saying he hoped the proceedings would prove that his name should not be associated with the word “rape.”