A Swedish court has rejected a request from prosecutors for WikiLeaks founder Julian Assange to be detained in absentia over a 2010 rape allegation.

Assange, an Australian national, is currently serving a 50-week sentence in Britain for skipping bail after spending seven years holed up in the Ecuadorean embassy in London to avoid extradition to Sweden.

He denies the rape accusation.

Today’s ruling means the Swedish prosecutor cannot at this stage request his extradition from Britain.

The United States has already requested Assange's extradition on conspiracy charges. If Britain were to grant that request before Sweden makes its own claim, Assange will be sent to the US.

Another factor pushing the Swedish prosecutor to act quickly is that the statute of limitations on the alleged rape runs out in August 2020.

However, defence lawyer Per Samuelson argued that Assange's imprisonment in Britain meant there was no flight risk.

"He is in prison for half a year at least, and he is detained on behalf of the United States. So there is no point detaining him in Sweden, too," Mr Samuelson said.

Swedish prosecutors dropped their rape investigation in 2017 but reopened it after Ecuador rescinded its grant of aslyum to Assange in April, allowing British police to arrest him.

"The (rape) investigation continues with interviews in Sweden. I will also issue a European Investigation Order in order to interview Julian Assange," prosecutor Eva-Marie Persson said in a statement after today’s ruling.

"No date has been set yet. We will constantly review the state of the investigation."

The US wants Assange extradited on charges relating to the public release by Wikileaks of a cache of secret documents, including assessments of foreign leaders, wars and security matters.

On 23 May, US authorities widened the scope of criminal charges against him to include espionage.

Britain's interior minister will have the final say on whether to extradite Assange to Sweden, the United States or neither.