In a letter to Prime Minister Rishi Sunak, Glasgow-based Positive Action in Housing, along with other refugee organisations, warned Ms Braverman’s actions at the centre in Manston had contributed to disease outbreaks of scabies and diphtheria. About 4,000 refugees, including children, are housed at the former Royal Air Force base, which was designed to process up to 1,600 people.
A statement from the Home Office insisted Ms Braverman had taken "urgent decisions to alleviate issues at Manston and source alternative accommodation".
This comes as chief inspector of prisons Charlie Taylor, who is due to release a report on the Manston facility on Tuesday, warned the speed of processing of refugees at the centre must be increased.
He said the centre, the largest detention centre in the UK, should be "a short-term holding facility which is supposed to process people through" in a matter of hours. Some people have been held there for as long as five weeks.
It called for the refugees to be recognised as individuals with “a face, a name and a story”.
The letter said: “Multiple media reports suggest that your recently reappointed home secretary Suella Braverman, while working under Liz Truss, directly blocked refugee transfers from a severely overcrowded ‘processing centre’ at Manston, Kent, leading directly to outbreaks of scabies and diphtheria.
"According to news reports, government officials warned Ms Braverman that she risked breaking the law by keeping refugees at the ‘processing centre’ for several weeks when it was intended to hold people for only 24 hours. Several government sources state Ms Braverman had blocked the transfer of thousands of asylum seekers to hotels during her first tenure as home secretary, even though the numbers were well above capacity.”
The letter referenced a side event at the Conservative Party conference last month, when Ms Braverman said it would be her “dream” to resurrect a controversial UK Government scheme to deal with people who arrived in the UK “illegally” and see the first plane take off to Rwanda, with asylum seekers on board.
Unveiled earlier this year to heavy criticism, the scheme would send refugees who arrive in the UK and are considered “inadmissible” to the African country, where they will stay if their application is granted.
The letter added: “It is shocking that your home secretary stoked xenophobia and anti-immigrant hatred to the point of blocking human beings from being transferred out of a disease-ridden, overcrowded camp. Her dreams of planes to Rwanda are real-life nightmares for desperate refugees.
"You said you want your Government to have 'integrity, professionalism and accountability at every level', yet you have just appointed Suella Braverman to be home secretary again, a week after she resigned for breaches of the ministerial code and security lapses. Now is the time act. As Prime Minister and Minister for the Union, we call on you to stop pandering to the far right, sack Suella Braverman and put in place someone who can do the job of home secretary with a shred of humanity and decency.”
The letter has been signed by hundreds of supporters.
The Home Office insisted any claims advice was deliberately ignored were "completely baseless" and said it was "right we look at all available options" to make decisions "on the latest operational and legal advice".