WikiLeaks chief spokesman Julian Assange has been arrested in the UK after turning himself in to authorities, the Metropolitan Police has said.
Assange, 39, of Australia, has been accused of one count of unlawful coercion, two counts of sexual molestation and one count of rape stemming from incidents with two women in Sweden in August.
He was arrested by the Metropolitan Police's Extradition Unit at 9:30am, and is due to appear later in City of Westminster Magistrates Court. A magistrate is likely to set bail for Assange, according to a police spokesman.
Assange has maintained that his encounters with the women were consensual, and Swedish prosecutors initially dropped rape charges.
However, Swedish director of public prosecution Marianne Ny re-opened the investigation into the rape charges and said she wanted to question Assange, who was allowed to leave Sweden after the incidents.
Since then, Assange has spent time in the UK, making few public appearances. The pressure has intensified on him as WikiLeaks began releasing portions of 250,000 secret US diplomatic cables late last month.
Some US politicians have called for his arrest, while the US Attorney General's office is investigating whether he could be charged under the Espionage Act for releasing the material.
The US Army has already charged Private First Class Bradley E Manning with mishandling and transferring classified information in connection with the cables and a video of an Apache helicopter shooting civilians in Iraq. He is believed to have passed the material to WikiLeaks.
Meanwhile, WikiLeaks has taken steps to make its infrastructure more resilient after its website came under repeated denial-of-service attacks. WikiLeaks was also booted from Amazon Web Services after it was briefly hosted on its servers.
But more than 350 other websites are now up that are distributing WikiLeaks' content, posing further difficulties for authorities seeking to halt the release of the material.