Leif Silbersky, Mr. Assange’s lawyer, said his client was innocent. Mr. Assange was questioned Monday by the police, Mr. Silbersky said, “and they said nothing about rape.”

Mr. Assange, a 39-year-old Australian, was initially investigated Aug. 20 on charges of rape and molestation after separate complaints from two women who had had separate sexual relationships with him. The rape inquiry was dropped within 24 hours, but the women who brought the complaints appealed for the investigation to be reinstated.

According to accounts the women gave to the police and friends, Swedish officials said, they had consensual sexual encounters with Mr. Assange that became nonconsensual. One woman said that Mr. Assange had ignored her appeals to stop after a condom broke. The other woman said that she and Mr. Assange had begun a sexual encounter using a condom, but that Mr. Assange did not comply with her appeals for him to stop when it was no longer in use.

Prosecutors have continued to investigate the lesser charge of molestation, which covers a wide range of offenses and carries penalties of up to a year in prison, and they said Wednesday that they were expanding that inquiry to consider charges of sexual coercion and sexual molestation.

Mr. Assange has said the charges are politically motivated.

WikiLeaks came under fire in July after posting tens of thousands of classified American documents related to the war in Afghanistan. The site has said it plans to post thousands of “more explosive” documents soon. The Swedish authorities have dismissed suggestions from Mr. Assange that the allegations were part of a program of “dirty tricks” against the site.