The Home Office is planning to deport vulnerable asylum seekers and suspected victims of trafficking on a new charter flight on Thursday, the Guardian has learned.

The flight will be going to Switzerland, Germany and Austria under Dublin convention legislation, EU rules that require asylum seekers to claim asylum in the first safe EU country they arrive in and not move from one to another.

EU countries can send people who have already made an asylum claim in one EU country back to that country, a right the UK retains during the Brexit transition period.

But lawyers for those scheduled for Thursday’s flight say they are exempt from this rule until they are properly assessed, because the Home Office cannot automatically deport those suspected to be victims of trafficking or people suffering from trauma and mental health problems caused by torture and other forms of persecution.

At least eight of those on the flight are known to be Eritrean and at least two are Iranian. Asylum seekers from countries such as Eritrea generally pass through Libya, known as a place where vulnerable migrants are trafficked.

The Home Office is supposed to refer suspected victims of trafficking to the National Referral Mechanism so they can be assessed. In recent days several high court injunctions have been obtained on behalf of Eritrean asylum seekers believed to be victims of trafficking but who have not been assessed as such. These injunctions will prevent them from flying on Thursday.

A 30-year-old who says he was a victim of torture and trafficking from Eritrea, spoke to the Guardian from Colnbrook Immigration Removal centre near Heathrow. He had just received the news that his removal was deferred following legal action on Wednesday which will prevent the Home Office putting him on Thursday’s charter flight. The court order states that he will not be removed from the UK on Thursday because he has a human trafficking claim. He claims he was tortured in Eritrea, escaped and arrived in Libya from where he hoped to cross the Mediterranean to Italy. He says he was held captive in Libya, forced into slave labour and tortured again.

He said: “I am very relieved that I will not be on the plane to Switzerland tomorrow, a country in Europe I was in before reaching the UK. I was threatened there with being sent back to Eritrea, where my life will be at risk.”

The man was dispersed to Yorkshire when he first arrived in the UK and was arrested when he went to a Home Office reporting centre. He was taken to Morton Hall immigration removal centre in Lincoln where he had an appointment to see a solicitor. But the Home Office then moved him to Colnbrook where he was unable to get an appointment last week. It is because he was unable to see a lawyer last week that the legal action to halt his removal on Thursday was lodged at the 11th hour before the charter flight.

All of those held in immigration detention also have the right to legal advice. The Guardian has seen a letter from the Immigration Law Practitioners Association and Detention Action to the Home Office, the Ministry of Justice and the Legal Aid Agency, raising concerns about access to legal advice for detainees ahead of the charter flight. Issues about access to legal advice were also raised in relation to last week’s charter flight to Jamaica.

In the case of Thursday’s charter flight the problems with access to legal advice relate to failures of legal surgeries known as the Detention Duty Advice scheme in some of the Home Office’s detention centres.

The letter states: “The people using the Detention Duty Advice Scheme and indeed those scheduled to be removed on tomorrow’s charter flight are people deprived of their liberty and separated from family and friends. They are people with often complex immigration, asylum and/or trafficking cases who need expert advice and representation, often urgently. Often, they cannot speak English. They may be exceptionally vulnerable as a result of torture, mental illness and/or trafficking and exploitation. Without proper advice and representation, they are denied access to justice.”

It adds: “We are not confident that the government can be satisfied that those scheduled to be removed on tomorrow’s charter flight have been given adequate access to justice as required by Home Office policy.”

Bella Sankey of Detention Action said: “The government is pressing ahead with another charter deportation flight, this time to a number of European countries to which it seeks to remove asylum seekers and vulnerable victims of trafficking. This is despite widespread concerns that the government’s system for the provision of legal advice in detention centres is in meltdown, with minimal solicitors available for at least three immigration removal centres last week and grave concerns that several firms are regularly in breach of their contractual obligations providing either no or poor advice to those detained.”

Rudy Schulkind, research and policy coordinator at Bail for Immigration Detainees who conducts regular research into the state of legal advice in detention centres, said: “We have noticed a deterioration in the quality of legal advice since changes made by the Legal Aid Agency in 2018. The stakes could not be higher for the individuals concerned. People held in immigration detention are deprived of their liberty and face enforced removal and separation from families and children and the possibility of torture or mistreatment upon return to their country of origin.”

Lawyers at Duncan Lewis have obtained last minute high court injunctions preventing some of the suspected victims of trafficking from flying on Thursday.

Toufique Hossain, director of public law at Duncan Lewis, said that these cases often have to be filed in the high court at the 11th hour by legal aid lawyers because previous lawyers have let down people in detention centres. “Access to justice is even more critical in these circumstances,” he said.

A Home Office spokesperson said: “Anyone who makes a trafficking or modern slavery claim has them properly considered and concluded before removal. The UK only ever returns those who both the Home Office and the courts are satisfied do not need our protection and have no legal basis to remain in the UK.

“Detainees are given ample opportunities to seek any legal advice they require whilst in immigration removal centres. We do not routinely comment on operational matters.”