Thirty-six child asylum seekers who previously lived in the Calais refugee camp have issued a legal challenge to the home secretary.

They claim Amber Rudd acted unlawfully in the way she handled their applications. It is the first time children from the camp have taken individual legal action against the government.

The children were dispersed across France after the site was dismantled on 31 October. Twenty-eight of those bringing the legal action have had their applications refused, while another eight are awaiting decisions from the Home Office.

Of the 28 refused, 11 are aged 14, seven are 15, nine are 16 and one is 17. Sixteen are from Eritrea, 11 are from Afghanistan and one is from Sudan. They have been dispersed to 15 reception centres around France.

In the legal challenge the government is accused of reneging on its commitment to bring vulnerable accompanied refugee children to the UK under section 67 of the Immigration Act, known as the Dubs amendment. This makes provision for particularly vulnerable children to come to the UK at the discretion of the government.

According to the children’s lawyers, the Home Office has failed to allow the relocation of many of the most vulnerable children to the UK, failed to give proper written decisions in refusing these applications and failed to use its discretion in response to extreme cases.

The judicial review focuses on the specific circumstances of one 14-year-old boy from Afghanistan as well as on the broader issues affecting all of the children.

The boy’s father helped Nato troops and was targeted by the Taliban as a result. The boy was shot in the neck by the Taliban when they came to the family home searching for his father. He was lucky to survive and fled his home country and travelled through eight countries to reach France.

Along the way he was buried alive while travelling in a car attacked by Iranian military, almost starved to death when he spent four days and nights in a Bulgarian forest, was physically and sexually exploited by people traffickers and was shot with rubber bullets and teargas while in the Calais camp.

His wrist was broken there when he was beaten by a French police officer wielding a baton. He tried to kill himself on four occasions while in Calais.

His legal team at Duncan Lewis Solicitors wrote to the Home Office on 2 November and 5 December to raise concerns about the boy’s condition but neither letter received a response.

While social workers have assessed him to be suffering from suicidal ideation and depression, and an independent psychiatrist assessed him to be suffering from post-traumatic stress disorder and to be a “traumatised and vulnerable boy” who needs treatment, a Home Office social worker who assessed him said there was no evidence that he had any particular emotional or psychological needs.

He was one of many children who were informed on 15 and 16 December that their applications to come to the UK had been unsuccessful.

He has twice expressed a desire to kill himself since being moved to a reception centre in France.

Amber Rudd is at the centre of legal dispute over the UK’s asylum policy. Photograph: Barcroft

In an initial response to the legal action, Home Office officials said they could not prioritise cases of children who had legal representatives, and that if the child felt the French authorities were not looking after him properly he could seek redress through the French courts.

Toufique Hossain, director of public law at Duncan Lewis Solicitors, said: “The government has rendered these children, including some as young as 13, to effectively be without any legal remedy until well into the new year, which is the earliest that the relevant Home Office officials have agreed to give reasons for refusing some of these children.”

He added that to date only 200 children had come to the UK and no more were expected from Calais.

“The way that this has all been handled by both the UK and French authorities is nothing short of shameful. It is morally reprehensible and, we argue, simply unlawful that these children have not been given written reasons as to why their applications were refused and that these children were told about the refusals in group meetings without a proper procedure in place.”

Some of the children whose applications have been refused have been sending SOS messages to the Guardian. One 16-year-old Sudanese boy in Biscarrosse, whose application to seek sanctuary in the UK has been refused, sent a series of messages on WhatsApp on Tuesday night, saying: “… am just tired of my life. Even I don’t know when or how I can sleep. All I know I just wanna do anything right now to forget.”

He referred to the staff at the reception centre as a “heartless machine”, adding: “I told them two weeks ago, please shoot us to relax us coz this not human, I would swear.”

A Home Office spokesperson said: “It would be inappropriate to comment on ongoing legal proceedings.”