A British judge on Tuesday denied bail for WikiLeaks founder Julian Assange after he told a London court he intends to fight his extradition to Sweden on sex crime allegations.

Judge Howard Riddle told Assange that he had "substantial grounds'' to believe the 39-year-old Australian wouldn't turn up for subsequent proceedings. He then put Assange into U.K. custody ahead of an extradition hearing.

Assange faces allegations of sex crimes in Sweden. He denies the accusations.

Assange appeared before City of Westminster Magistrates' Court after turning himself in to Scotland Yard earlier Tuesday to face a Swedish arrest warrant.

The founder of the secret-spilling website was asked whether he understood that he could consent to be extradited to Sweden, where he faces allegations of rape, molestation and unlawful coercion.

Clearing his throat, Assange said: "I understand that and I do not consent."

Assange denies the allegations, which stem from a visit to Sweden in August. Assange and his lawyers claim the accusations stem from a "dispute over consensual but unprotected sex," and have said the case has taken on political overtones.

Swedish prosecutor Marianne Ny has rejected those claims.