Swedish prosecutors said on Friday they had asked for Assange's approval to question him in London, a U-turn after years of insisting he must go to Stockholm for questioning about alleged assaults against two women in 2010.

Assange denies the allegations, which are not related to WikiLeaks' publication of U.S. military and diplomatic documents, also in 2010. He refused to go, arguing Sweden could send him on to the United States where he might face trial.

One of Assange's lawyers said he welcomed the request but expressed concern the process could take time because approval was needed from British and Ecuadorian authorities.

"He has been nagging for this for four years. He wants nothing more than to have an opportunity ... to give his version of what happened and to clear his name," Assange's lawyer Per Samuelson told Reuters.

Ecuador's embassy in London could not immediately be reached for comment.