Women’s groups have added to pressure on Sajid Javid to ensure Julian Assange is extradited to Sweden. Failure to do so would effectively endorse “rape culture”, they claim.

A coalition of campaigners representing survivors of sexual violence urged the home secretary to focus on the unresolved rape allegations emanating from Sweden against Assange. They fear that US charges – relating to WikiLeaks’ disclosures – may be given priority in the UK.

The United States has filed a provisional extradition request for Assange while Sweden continues to weigh up whether to reopen an investigation into rape and sexual assault allegations against the 47-year-old co-founder of WikiLeaks. On occasions, when there are competing extradition requests, the home secretary decides which country should take priority.

Sarah Green, co-director of End Violence Against Women, an alliance of more than 80 organisations, said Assange’s portrayal by some as a victim was an affront to rape survivors.

“He’s always benefited from his cult hero status, painting himself as a victim and being very righteous. Yet this is about rape, it’s what he is accused of. It’s extremely serious.”

Green added that there was widespread disquiet that the rape allegations were being smothered by the broader debate on Assange, who is being held in London’s Belmarsh prison after his arrest on Thursday. He had spent the previous seven years in Ecuador’s London embassy.

“The constant downplaying of rape that lies at the centre of this is undignified. This is serious – the harm rape does, even the impact it has when people dangle it around in the news as though it’s a trivial part of the story,” added Green.

Writing in the Observer, the Labour MP Jess Phillips confirmed growing unease over the debate, highlighting a parliamentary exchange on Thursday between the shadow home secretary Diane Abbott and Javid, in which both appeared to play down the allegations of sexual violence and rape. Abbott responded to criticism with a letter yesterday saying that if the Swedish authorities requested his extradition to face charges of rape it should be granted and added that “due justice should be followed”.

Phillips writes: “The first and most pressing case he [Assange] should answer is the one where he has delayed, and therefore denied, possible justice to two Swedish women. The UK government should support his extradition to Sweden before they even begin to consider any pressure from the US,” she wrote. Phillips is among one of more than 100 MPs and peers to have signed a letter urging Javid to ensure Assange faces authorities in Sweden if they request extradition.

Further pressure came from Sweden itself, with one of the women who accused Assange of sexual assault calling for him to be extradited to the Scandinavian country, adding that she would still be prepared to testify in court. Her case concerns allegations of unlawful coercion and molestation against Assange, but was halted in August 2015 due to time restrictions.

On Saturday she told the Observer that developments following Assange’s arrest had substantiated her anxiety that Assange’s seven-year stay in Ecuador’s embassy was more about evading justice than his extradition to the US over one of the largest ever leaks of government secrets in 2010.

“My suspicions have been strengthened that refusing to cooperate with the Swedish police and courts, and finally leaving Sweden, had nothing to do with his fear of extradition to the US, as has been claimed. It is more likely that this was about him not wanting to take responsibility for treating other people badly,” she said, requesting anonymity.

The rape accusation dates from August 2010, when the alleged victim, who says she met Assange at a WikiLeaks conference in Stockholm, filed a complaint. She has accused him of having sex with her while she was sleeping, and without using a condom, despite her repeated refusals to have unprotected sex with him.

Meanwhile, Assange’s lawyers have warned that their client will not receive a fair trial if he is extradited to the US because of the “politicised nature” of the issue. Jennifer Robinson told the Observer: “There are real questions to be asked about the political nature of this debate and how much it has been politicised.”

Assange’s lawyer also shed light on the cause of his pale, unkempt appearance as he was removed from the embassy. Robinson said: “He’s been without sunlight, has dental problems and a frozen shoulder that is causing him a huge amount of pain. His health has deteriorated significantly.” His legal team have requested urgent medical attention since he was transferred to the maximum security prison.

“The US extradition request and the indictment itself – the fact it is alleging conspiracy with a source – means a publisher or journalist could be accused of conspiracy with a source,” said Robinson. “It’s a terrifying precedent for all journalists.”

She is part of a formidable team that includes lawyers who have quashed past US attempts to extradite hackers. Assange has always denied all the rape allegations.