Assange, 39, is wanted in Sweden for questioning about allegations of rape, sexual molestation and unlawful coercion, and an arrest warrant was received by London's Metropolitan Police earlier on Monday, a police source told Reuters.

The Australian, whose WikiLeaks website is at the centre of a row over the release of secret US diplomatic cables, has denied the allegations.

“Late this afternoon after close of business I got a call from the police who said that they had received an extradition request from Sweden,” London lawyer Mark Stephens told BBC television.

“Their request is to interview Julian Assange. He's not been charged with anything."  “We are in the process of making arrangements to meet with the police by consent in order to facilitate the taking of that question and answer that is needed.” He said the interview will happen in the “foreseeable future” but could not give an exact timescale.

Sweden's prosecution authority said it had given British police all the information they requested, after a series of apparent legal hitches.

British media had reported that Assange was in Britain after WikiLeaks released a trove of cables exposing the inner workings of American diplomacy. Assange's legal team has said it will mount a challenge in the British courts to any Swedish attempt to have him arrested and sent to Sweden.

Stephens was not immediately available for further comment.

Once London received a copy of the warrant it deemed legally satisfactory, a police move to arrest Assange was likely to occur quickly, an official source familiar with legal discussions between authorities in the two countries said.

The Swedish prosecution authority at first opened, then dropped and then re-opened the investigation of allegations by two Swedish women. Assange's Swedish lawyer has said his client believed foreign powers were influencing Sweden.

The latest release listed details of sites around the world which the United States considers vital to its interests, including drug companies and energy installations.

Swiss postfinance, the banking arm of state-owned Swiss Post, has closed an account used for WikiLeaks donations because Assange has no residency in Switzerland, a spokesman for the bank said. The online payment service PayPal has also suspended WikiLeaks' account.

US Attorney General Eric Holder said on Monday the Obama administration was considering using laws in addition to the US Espionage Act to possibly prosecute the release of government information by WikiLeaks.

Assange has said he and colleagues are taking steps to protect themselves after death threats. – Reuters