Pressure is mounting on the foreign secretary, Boris Johnson, to intervene in the case of Amina al-Jeffery, the 21-year-old British national who claims to have been imprisoned by her father in Saudi Arabia, as fears build that she is in “grave and immediate danger” following the publicity around her case.

In a ruling earlier this week, a British judge ordered Mohammed al-Jeffery to return his daughter to the UK by 11 September, following claims he had kept her “locked up” in the family home after she had kissed a man.

Rights groups have now warned the government against waiting until the five-week deadline is reached, saying al-Jeffery’s safety is at risk for as long as she is in the country. Geraint Davies, Jeffery’s MP in Swansea, has written a letter to Johnson seeking immediate action in the form of “an air ticket, passport and safe passage home without delay”.

He told The Guardian: “Amina may be at risk of being punished for bringing the case to light. I’m concerned the father, having lost the case, may act inappropriately. Meanwhile where is Boris and why hasn’t he come out and said anything?

“This has wider ramifications because if British citizens can’t be protected abroad, it may give a green light to other cases.”

Jeffery, who was born in Wales but also holds Saudi Arabian citizenship, says she was tricked into travelling to Jeddah in April 2012 under the guise of going on holiday not long before her 17th birthday.

She described how her father, who removed her from the UK on account of her “un-Islamic” behaviour, kept her in solitary confinement for four months after Saudi authorities arrested her for kissing an American who has since been deported.

In December last year she managed to send emails to her British lawyer claiming her father beat her, put bars on her bedroom door and denied her access to the bathroom, forcing her to urinate in a cup. He denies the allegations.

More than 50 women’s rights groups and campaigners signed a letter to the Foreign Office, published in the Guardian this week, which stated the father “was refusing to co-operate with the consul in Jeddah”.

They wrote: “Given the problems of enforcing this order in Saudi Arabia, we call upon the FCO to ensure that the order is complied with.”

The London-based Iranian and Kurdish Women’s Rights Organisation supports women who have been victims of “honour” based violence. It’s director Diana Nammi, who is among those to have signed the letter, warned that if Jeffrey was not safeguarded straight away she could suffer abuse.

“We know from our experience as soon as someone asks for help, the threat escalates,” she said.

Nammi, who is also calling for the government to extradite Jeffery’s father, added: “We must act now and ensure Amina is treated no differently from a British white girl.”

On Wednesday, Mr Justice Holman made the landmark ruling at the family division of the high court in London that Jeffery was entitled to protection under British law, despite her father claiming that her captivity was normal in a country with strict Islamic rules.

He ordered Mohammed al-Jeffery to give his daughter her passports and allow her to return to Britain within five weeks. The judge acknowledged there are no reciprocal arrangements between the UK and Saudi but said he had a moral and practical hold over the father, whose wife and other eight children remain living in Wales.

But Pragna Patel, director of the charity Southall Black Sisters, accused the court’s response as making a “mockery of the government’s much vaunted commitment to addressing crimes of ‘honour’.”

She said: “By allowing the father time to bring her back in September, there is a complete disregard to the significant risk of harm she faces as each day goes by.

“Yet again it would seem diplomatic and financial relations with the Saudis take precedence over gross human rights abuses.”

Jeffery’s father, who denies the allegations, said he took his “rebellious” daughter to Saudi Arabia because since the age of 14 she had been going to clubs, smoking marijuana, drinking alcohol and spending time with older men. The 62-year-old could face contempt of court proceedings if he returns to Britain without complying with the order.

Anne-Marie Hutchinson, representing his daughter, said there was no reason to assume her father would not obey the order.

The Foreign Office has confirmed they will continue to raise the case with the Saudi authorities. A spokesperson said: “We have been providing assistance to her since the case was first brought to our attention. British embassy staff have met with her to check on her welfare and helped her to speak to lawyers in the UK.”