WikiLeaks founder Julian Assange surrendered to London police on Tuesday as part of a Swedish sex-crimes investigation, the latest blow to an organization that faces legal, financial and technological challenges after releasing hundreds of secret US diplomatic cables.

Assange was due at Westminster Magistrate's Court later on Tuesday. If he challenges his extradition to Sweden, he will likely be remanded into custody or released on bail until another judge rules on whether to extradite him, a spokeswoman for the extradition department said on customary condition of anonymity.

Since beginning to release the cables last week, WikiLeaks has seen its bank accounts canceled, its web sites attacked and the US government launch a criminal investigation, saying the group has jeopardized national security and diplomatic efforts around the world. It has also seen supporters come to its aid by setting up over 500 mirror sites around the world.

The legal troubles for Assange, a 39-year-old Australian, stem from allegations leveled against him by two women he met while in Sweden over the summer. Assange is accused of rape and sexual molestation in one case and of sexual molestation and unlawful coercion in another.

Assange denies the allegations, which his British attorney Mark Stephens says stem from a "dispute over consensual but unprotected sex." Assange and Stephens have suggested that the prosecution is being manipulated for political reasons.

A spokesman for WikiLeaks called Assange's arrest an attack on media freedom and said it won't prevent the organization from releasing more secret documents. "This will not change our operation," Kristinn Hrafnsson told The Associated Press.

WikiLeaks has angered the US government by releasing tens of thousands of secret US military documents, followed by the ongoing release of what it says will eventually be a quarter-million cables from US diplomatic posts around the world. It provided those documents to five newspapers, which have been working with WikiLeaks to edit the cables for publication.

The campaign against WikiLeaks began with an effort to jam the website as the cables were being released. US Internet companies Amazon.com, Inc., EveryDNS and PayPal, Inc. then severed their links with WikiLeaks in quick succession, forcing it to jump to new servers and adopt a new primary Web address — wikileaks.ch — in Switzerland.

Swiss authorities closed Assange's bank account Monday, and MasterCard has pulled the plug on payments to WikiLeaks, according to technology news website CNET. A European representative for the credit card company didn't immediately return a call seeking comment.

The attacks appeared to have been at least partially successful in stanching the flow of secrets: WikiLeaks has not published any new cables in more than 24 hours, although stories about them have continued to appear in The New York Times and Britain's The Guardian, two of the newspapers given advance access to the cables.

WikiLeaks' Twitter feed, generally packed with updates, appeals, and pithy comments, has been silent since Monday night, when the group warned that Assange's arrest was imminent.