A British judge has ruled against releasing WikiLeaks founder Julian Assange on bail.

Lawyers for WikiLeaks founder Julian Assange had argued there is no risk of him absconding, pending an appeal against a decision not to extradite him to the United States.

Lawyers for the US government, however, told the court there were "no conditions that could guarantee his surrender" if Assange were released from custody.

"I am satisfied that there are substantial grounds for believing that if Mr Assange is released today he would fail to surrender to court to face the appeal proceedings," Judge Vanessa Baraitser said.

Crowds of supports had gathered outside the court awaiting the ruling.

A London court on Monday blocked his extradition to the United States, where the 49-year-old faces a number of charges for publishing hundreds of thousands of secret documents online. Judges said he was a high suicide risk if handed over.

The US Department of Justice called the extradition ruling "extremely disappointing" and said it will appeal. The process, however, will likely take months, particularly given the current backlog of cases caused by the Covid-19 pandemic.

Even if the US loses again, it could also appeal to the UK Supreme Court, which would mean longer delays.

Assange had remained in the high-security Belmarsh prison in southeast London pending the latest hearing at Westminster Magistrates' Court in central London.

His lawyers tried to get him released in March on the grounds that he was at risk from Covid-19. Judges then rejected that argument, saying Assange could skip bail if released. 

The WikiLeaks founder was arrested in 2019 after seeking sanctuary at the Ecuadorian Embassy in London in 2012. He was holed up there for years after Sweden issued an arrest warrant in connection with sexual assault allegations.

British police dragged Assange out of the embassy in April 2019 after Ecuador revoked his citizenship. He was arrested for breaching his bail terms in connection with the Swedish case, which was later dropped due to lack of evidence.

A court handed him a 50-week jail term, but Assange has remained in prison pending the conclusion of the American extradition request. The UN called the sentence "disproportionate."

Disappointment over bail refusal

"This is a huge disappointment," Stella Morris, Assange's partner told reporters outside court on Wednesday.

"Julian should not be in Belmarsh Prison in the first place. I urge the Department of Justice to drop the charges and the President of the United States to pardon Julian."

Director of International Campaigns at NGO Reporters without Borders, Rebecca Vincent called the court's decision to refuse bail "unnecessarily cruel."

That was the first time I’ve had direct sight of Assange since February (as at the Old Bailey I could only access the overflow court to watch a live stream). He looked better than he did at Woolwich, was alert and following proceedings. 17/

— Rebecca Vincent (@rebecca_vincent) January 6, 2021

The charges against Assange

The Australian is still wanted on 18 charges in the United States and faces a maximum 175-year sentence if convicted. The charges are related to the 2010 release by WikiLeaks of 500,000 secret files detailing aspects of military campaigns in Afghanistan and Iraq.

The US government also alleges that he helped intelligence analyst Chelsea Manning steal the 2010 documents before exposing confidential sources around the world.

The transition team for US President-elect Joe Biden has so far declined to comment as to whether the incoming administration will pursue the case.

Manning was pardoned by former President Barack Obama at the end of his second four-year term. But she remained in jail from May 2019 until December 2020 for refusing to testify before a grand jury investigating WikiLeaks.

Court: Assange knew what he was doing

Assange and his lawyers have long argued that the protracted case against him is politically motivated.

District Judge Vanessa Baraitser on Monday said Assange would have been "well aware" of the effects of his leaking of secret documents, and his actions went "well beyond" the role of a journalist.

But she said his mental health would probably deteriorate in the US penal system "causing him to commit suicide."

She rejected US experts' testimony that Assange would be protected from self-harm, noting that others, such as disgraced US financier Jeffrey Epstein, had managed to kill themselves in custody despite supervision.

Following Monday's ruling, Mexican President Andres Manuel Lopez Obrador offered Assange political asylum.

Australian Prime Minister Scott Morrison said on Tuesday that Assange was "free to return home" to Australia once the legal cases against him had concluded.