WikiLeaks founder Julian Assange is to be extradited to Sweden to face allegations of rape and sexual assault. Assange will appeal, his legal team confirmed. If this is unsuccessful, he will be extradited to Sweden in 10 days.

Delivering his ruling at a hearing at Belmarsh magistrates court in London, the chief magistrate Howard Riddle systematically dismissed each of the defence’s arguments against Assange’s extradition.

Assange’s legal team had disputed that Swedish prosecutor, Marianne Ny, had the authority to issue a European arrest warrant, but the judge ruled that she did possess this authority and the warrant issued was valid.

Ny’s credibility had been questioned by the defence team, but the judge dismissed those doubts which he said amounted “to very little”. The retired judge who criticised her, Brita Sundberg-Weitman, had no first-hand knowledge and no evidence as to source of her opinion, he said.

The defence had also argued that the allegations against Assange were not offences in English law and therefore not extraditable. But the judge said the three alleged offences against Miss A, sexual assault and molestation, met the criteria for extradition offences and a fourth against Miss B, an allegation of rape, “would amount to rape” in this country.

In his summary the judge also accused Assange’s Swedish lawyer, Björn Hurtig, of making a deliberate attempt to mislead the court. He added that Assange had clearly attempted to avoid the Swedish justice system before he left the country, saying “It would be a reasonable assumption from the facts that Mr Assange was deliberately avoiding interrogation before he left Sweden.”

While Riddle acknowledged that there had been “considerable adverse publicity against Mr Assange in Sweden”, including from the prime minister, if there had been any irregularities in the Swedish system, the best place to examine them in a Swedish trial, he said.

Assange has been fighting extradition since he was arrested and bailed in December. He has consistently denied the allegations, made by two women in August last year.

At a two-day hearing earlier this month, his legal team argued that Assange would not receive a fair trial in Sweden. They said the European arrest warrant (EAW) issued by Sweden was invalid because the Australian had not been charged with any offence and that the alleged assaults would not be legitimate extraditable offences.

Assange fears that an extradition to Sweden would make it easier for Washington to extradite him to the US on possible charges relating to the release by WikiLeaks of leaked US embassy cables.

If this was to happen, Sweden would have to ask permission from the UK for the onward extradition. No such charges have been laid, though the website’s activities are under investigation in the US.

The most serious of the four allegations relates to an accusation that Assange, during a visit to Stockholm in August, had sex with a woman, Miss B, while she was sleeping and without a condom, and without her consent. Three counts of sexual assault are also alleged against another woman, Miss A. If found guilty of the rape charge he could face up to four years in prison.

Assange will now be detained in custody, because there is no system of bail in Sweden, until a possible trial or release.

The Australian ambassador to Sweden, Paul Stephens, wrote to the country’s justice minister last week to insist that, if extradited, any possible case against Assange “would proceed in accordance with due process and the provisions prescribed under Swedish law, as well as applicable European and international laws, including relevant human rights norms”.

EAWs were introduced in 2003 with the aim of making extradition swifter and easier between European member states. But campaigners have raised concerns about the application of the warrants, arguing that they are sometimes applied before a case is ready to prosecute, and that while they were originally intended to counter terrorism, their use has greatly increased. Seven hundred people were extradited from the UK under the system last year.