Julian Assange has been refused bail by a judge who this week rejected a US request to have him extradited to face espionage and hacking charges.

The co-founder of WikiLeaks has been held at Belmarsh prison in south-east London for the past 18 months after he was evicted from the Ecuadorian embassy, where he sought asylum for seven years.

Two days after her ruling against the US extradition request, which is being challenged, district judge Vanessa Baraitser said the 49-year-old “still has an incentive to abscond from these, as yet unresolved, proceedings” and she was satisfied he would fail to surrender if bailed.

“As a matter of fairness the US must be allowed to challenge my decision,” said the judge, sitting at Westminster magistrates court after overseeing the extradition hearing at the Old Bailey earlier this week and last year.

Assange “had already demonstrated a willingness to flout” the orders of the court, she said, and people who had previously put their trust in him and given sureties had been let down and had their money forfeited. She was also satisfied that his mental health was being managed at Belmarsh.

Making the bail application, Assange’s lawyers said when he absconded eight years ago to enter the Ecuadorian embassy was in “totally different circumstances” and he now had the opportunity to be reunited in the UK with his partner and two young children. He would live at their address and wear an ankle tag.

After Monday’s rejection of the US extradition request, Edward Fitzgerald QC said Assange “now has every reason to stay in this jurisdiction, where he has the protection of the rule of law and this court’s decision”.

“The experience of going to the Ecuadorian embassy was in the end an extremely unpleasant experience leading to him being confined for seven years and a change in the government leading to a change in the position. That is something he is never likely to repeat,” he added.

The bail application was contested by Clair Dobin, a barrister appearing for the US authorities, who said the court “should be under no illusions” as to readiness of other states to offer protection to Assange.

She referred to an offer of asylum the president of Mexico had extended to Assange following Monday’s ruling. Assange would not necessarily have to leave the UK, she said, adding: “He would just have to enter another country’s embassy.”

His past activities, including involvement in helping the US whistleblower Edward Snowden, showed Assange had resources and “the sheer wherewithal” to arrange his own flight.

However, Fitzgerald said Mexico’s offer was “quite clearly” intended come into effect after the legal proceeding in the UK had concluded and provide Assange with an option of refuge elsewhere in the world were he to choose to leave the UK.

“It was not a suggestion that they would welcome him into their embassy,” said Fitzgerald.

There was a dispute over Covid-19 rates in Belmarsh prison, where Assange’s lawyers maintained there had been a severe outbreak among dozens of prisoners on the wing where the 49-year-old was being held.

“In any view, the [Covid-19 in prison] position is worse now than before Christmas and he would be safer isolating with his family in the community subject to severe restrictions rather than at Belmarsh, which clearly has had a very significant outbreak,” said Fitzgerald.

The court also received confirmation that lawyers for the US would appeal against Monday’s extradition ruling. While rejecting arguments that Assange would not get a fair trial in the US, on Monday Baraitser blocked extradition on the basis that procedures in prisons there would not prevent him from potentially taking his own life.

The American prosecutor seeking to put Assange on trial in the US has meanwhile said he was uncertain if Joe Biden’s incoming White House administration would continue to seek the extradition of the WikiLeaks co-founder.