A panel of seven supreme court justices will hear Julian Assange's appeal against extradition to Sweden to face accusations of rape and sexual assault.

The large number of judges employed reflects "the great public importance of the issue", according to a statement from the UK's highest court.

The supreme court said there would be a two-day hearing of the appeal by the Australian-born founder of WikiLeaks beginning on 1 February.

A panel of three supreme court justices – Lord Hope, Lord Mance and Lord Dyson – examined Assange's application on Friday following the high court's "certification of a point of law of general public importance".

At full strength the supreme court has 12 justices. The more significant the case, the greater number of judges will hear it. The central issue to be examined, the court said, is "whether a prosecutor is a judicial authority."

Assange has been detained under a European arrest warrant (EAW) issued by a Swedish public prosecutor over allegations that he sexually assaulted two women during a visit to Sweden in August 2010. He denies the claims.

At an earlier hearing his barrister, Mark Summers, argued that public prosecutors were not "judicial authorities" able to issue warrants under extradition law, and so the warrant was invalid. If Assange, 40, loses this appeal he may still be able to appeal against extradition to the European court of human rights in Strasbourg.

Meanwhile, Assange has moved from Ellingham Hall, Norfolk, where he has been staying for more than a year at the home of Vaughan Smith, owner of the Frontline Club for journalists.

Assange and a group of his supporters had been holed up in the country house with Smith and his family including his pregnant wife. Assange's bail conditions meant he had to sign in at nearby Bungay police station every day.

There have been times when as many as 20 people from WikiLeaks stayed at the house.

"I'd open a cupboard and another one would fall out," Smith has joked.

On one occasion Assange reportedly upset the estate's farm manager when he let out some pigs to make a video about credit card companies that have denied him the means to raise donations.

"My wife is eight months pregnant and they felt if they stayed longer it would not be right," Smith said on Friday. "I think Julian thinks a year is a long time to be with anybody."

Smith has spoken proudly of his decision to stand by Assange and support him through the legal process of challenging his extradition, but he has also admitted to minor domestic bother.