Priti Patel is said to have threatened to sue her successor at the Home OfficeSuella Braverman in a dispute about overcrowding at the Manston asylum processing centre.
The extraordinary row follows the controversy over “Dickensian” conditions at the cramped Kent facility where thousands asylum seekers were held for several weeks at the end of autumn.
After being informed she would be blamed for the overcrowding problem, Ms Patel phoned cabinet secretary Simon Case and said if Ms Braverman did not retract claims she would start legal action for defamation, according to the Mail on Sunday.
A source told the newspaper: “Priti worked round the clock when she was home secretary to tackle this problem and erupted when she was told that her record was being criticised. Simon Case had to calm her down.”
Government sources had briefed negatively about Ms Patel’s time in charge at the Home Office when the overcrowding furore flared up in October.
Immigration minister Robert Jenrick told MPs that he had inherited the problem after “insufficient accommodation was procured over a sustained period” by the Home Office.
Ms Patel is understood to deny this claim, insisting no changes were made to the system of placing people in hotels under her watch.
Allies of the former home secretary have defended her immigration reforms, and claim the government had not properly pushed to implement the Nationality and Borders Act.
It comes as Mr Braverman’s team said they were optimistic it could deport the first authorised migrants to Rwanda “before the summer”.
Cabinet Office minister Oliver Dowden said the government wants to “get cracking” on sending migrants on a one-way trip to Rwanda, with plans being made for summer deportations.
“As soon as that [court] process is through – and I’m confident our policy is lawful – we will get cracking straight away with the Rwanda policy and use that as a tool in our armoury.”
On her weekend trip to Rwanda, Ms Braverman expanded the agreement with the country to incorporate all those deemed to have illegally entered the UK as opposed to solely asylum seekers.
The revised deal is aimed at ensuring that all authorised entrants would be detained and removed under the Illegal Migration Bill – irrespective of the claim they bring, including asylum, human rights, modern slavery or nothing at all.
Ms Braverman also said the UK could withdraw from the European Convention of Human Rights (ECHR) in future. She said the bill as it stands “does not take us out of the ECHR”, but added: “Nothing is off the table, ultimately.”
Ms Braverman told reporters in Rwanda that there are “serious issues with the balance that’s currently being struck” by the European court in Strasbourg over human rights law.
The Refugee Council said Rishi Sunak and Ms Braverman’s legislation would mean as many as 45,000 children being effectively barred from obtaining refugee status in the UK.
The bill is due to bring forward the removal of migrants arriving by small boats and other unauthorised routes in a period of 28 days.
Asked whether the legislation could see those appealing against their relocation fly back to Britain, Ms Braverman said: “The bill dramatically, dramatically reduces the opportunity for people to make spurious claims.”
The Court of Appeal hears a challenge against the Rwanda plan in April before offering a judgment in June.
But if it goes to the Supreme Court, the government will have to decide whether to start deportation flights immediately and offer a commitment to return people to the UK if the judgment ultimately goes against them.
The Independent understands that Tory moderates are discussing how best to amend the bill at the next stage – focusing on stopping child detention and any watering down of modern slavery protections.
However, right-wing Tory MPs are also understood to be drawing up plans to further toughen the bill with an amendment to pull the UK out of the European Convention of Human Rights (ECHR).
Labour’s Lisa Nandy slammed the “unethical, unworkable” Rwanda policy and suggested money from the £140m deal should be used to aid the National Crime Agency’s efforts to tackle criminal gangs profiting from Channel crossings.
She said the government’s rhetoric had got “increasingly outlandish”, adding: “What is the government actually doing? So far they’ve done several PR opportunities and photo ops.”
On Saturday, Ms Braverman visited housing which is set to be used for migrants. Those arriving from the UK would be housed in hostels and hotels in the short term, before moving onto long-term housing arrangements.
Ms Braverman joked about interior designers during her visit to “offshore processing” accommodation on Saturday. Looking inside one of the properties, she said: “These houses are really beautiful, great quality, really welcoming and I really like your interior designer. I need some advice for myself.”
Lib Dem leader Ed Davey said the Rwanda trip was “an expensive distraction from the immoral, unworkable Braverman bill”.