London (CNN) -- An appeal by Swedish authorities against the decision to grant bail to WikiLeaks founder Julian Assange will take place Thursday at the High Court in London, a spokesman said.

The court did not specify a time.

Assange handed himself over to London police last week to answer a European arrest warrant from Sweden, which wants to question him over alleged sex crimes.

He was granted bail Tuesday, but he remained behind bars because a lawyer for Swedish prosecutors immediately filed an appeal.

Assange is facing accusations of rape, sexual molestation and illegal use of force stemming from separate incidents in August in Stockholm. He could be sentenced to two years in prison if convicted. He has not been charged with a crime.

His lawyers deny the allegations and have vowed to fight any attempts at extradition.

The magistrate agreed to grant bail Tuesday after Vaughan Smith, a former British army officer who founded a popular London journalist haunt called the Frontline Club, testified that Assange could stay at his mansion in Suffolk, northeast of London.

Smith will keep Assange "if not under house arrest, at least under mansion arrest," said defense attorney Geoffrey Robertson.

Assange finds celebrity supporters

Under the terms the magistrate set, Assange must post bail at 200,000 pounds (about $315,000) plus two sureties of 20,000 pounds each (about $31,500). Assange's passport must remain with police, and he will be monitored by a location tag.

Assange must be at Smith's mansion for at least four hours overnight and four hours during the day. He will be required to report to police daily between 6 and 8 p.m. The next court hearing on Assange's extradition was scheduled for January 11.

Outside the court, about 100 people demonstrated in support of Assange, holding signs saying "Julian Assange is a political prisoner" and "Why are you shooting the messenger?" and "This is not 1984."

Judge Howard Riddle denied Assange's first request for bail at a hearing on December 7 on the grounds that there was a risk he would fail to surrender.

Tuesday, he cited four reasons for his insistence a week earlier to keep Assange in jail: his lack of fixed residence, confusion over when and how he last entered the United Kingdom, the evidence against him in Sweden, and a dispute over whether Assange is wanted only for questioning or for prosecution.

Smith's offer of his mansion satisfied Riddle on the question of an address, and testimony from someone who arrived in Britain with Assange from Switzerland answered that question, he said.

He said he was not taking a position on the Swedish evidence against Assange, and that a future hearing would have to determine whether Assange was wanted for questioning or prosecution.

WikiLeaks' release of thousands of secret U.S. diplomatic and military documents is under criminal review in the United States. The website angered U.S. authorities last month by publishing the first of some 250,000 confidential U.S. diplomatic cables.

Last week, U.S. Attorney General Eric Holder said he had authorized "significant" actions related to a criminal investigation into WikiLeaks' publication of the materials but has declined to elaborate.

Only a small fraction of the 250,000 U.S. State Department documents have been released and more are being published daily.

U.S. authorities and other Western leaders say the documents' publication threatens lives and national security. WikiLeaks and its supporters say that the public has a right to know what is going on behind diplomatic doors.