Sweden reopened an investigation into a rape allegation against WikiLeaks founder Julian Assange on Monday and will seek to extradite him from Britain, a potential setback to efforts by the United States to put him on trial over a huge release of secret documents.

Deputy Chief Prosecutor Eva-Marie Persson told a news conference in Stockholm she would continue a preliminary investigation that was dropped in 2017 without charges being brought after Assange took refuge in the Ecuadorean Embassy in London.

Assange, who denies the accusation, was arrested in Britain last month after spending seven years hiding inside the embassy.

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The Swedish prosecutor said she would request Assange be detained in his absence on probable cause for an allegation of rape and that her office would issue a European arrest warrant — the start of the extradition process.

The United States is also seeking to extradite him on conspiracy charges relating to the public release by Wikileaks of a cache of secret documents, including assessments of foreign leaders, wars and security matters.

The British courts will have to rule on the two extradition requests, with Home Secretary Sajid Javid having the final say on which one takes precedence.

“I am well aware of the fact that an extradition process is ongoing in the U.K. and that he could be extradited to the U.S.,” Persson said.