Suella Braverman was unable to say when new detention centres for migrants who arrive on small boats will be built, or when the first removals would happen – or the cost of the policy.
It comes as Dame Rachel De Souza – the government’s Children’s Commissioner for England – said she was “deeply concerned” about the bill and was “seeking urgent clarity” from the Home Office.
The home secretary provided few details when grilled on the Rishi Sunak plan to ban people arriving via the English Channel from claiming asylum before deporting them.
Asked when the government would provide new facilities needed to hold thousands of detainees for up to 28 days, Ms Braverman told Sky News: “I’m not going to give precise dates”.
The minister said “we are rolling out new detention space”, adding: “We’ve got logistical challenges that we’re always overcoming. But very, very soon we will be expanding our detention capacity to meet the need.”
Questioned on when the first removals would begin, the Tory cabinet minister said: “I can’t give you precise dates, we have lots of processes which are in train.”
Ms Braverman said the first flights to Rwanda – with whom the UK struck an offshore processing deal – would depend on the legal challenge currently going through the courts.
The home secretary said it would be clear by the time of the general election whether the Government had succeeded in tackling the problem.
“It’s vital that we fix this problem. I think it will be very clear by the time of the next election whether we have succeeded or not,” she told BBC Radio 4’s Today programme.
Ms Braverman also defended her controversial claim to MPs that “there are 100 million people around the world” who could qualify for asylum protection in the UK and “they are coming here”.
ITV’s Good Morning Britain host Susanna Reid asked her: “On what planet is that likely and how is that not inflammatory language?”
The home secretary said the 100 million was a UNHCR figure referred the number of people forcibly displaced, before adding: “Many of them are coming heading to the United Kingdom.”
Tory peer Gavin Barwell said Ms Braverman should be “utterly ashamed of herself for resorting to the language of extremists”.
Caitlin Boswell of the Joint Council for the Welfare of Immigrants (JCWI) told The Independent she was “horrified” to hear “such inflammatory, scaremongering rhetoric,” adding: “Aside from stoking fear and hate, her comments are also complete codswallop.”
The cabinet minister was also challenged by Sky News host Kay Burley, who asked Ms Braverman: “As a barrister, are you completely comfortable with breaking the law?”
Ms Braverman insisted the bill does not break the law – despite admitting telling Tory MPs in a letter that there is a more than 50 per cent chance the legislation may not be compatible with the European Convention on Human Rights (ECHR).
Ms Braverman said the government was “pushing the boundaries” and “testing innovative and novel legal arguments” with its small boats plan.
“I believe that our measures are compatible with the international legal obligations,” she told BBC – but said “out of an abundance of caution”, she had issued the letter to MPs about possible incompatibility with the ECHR.
The Children’s Commissioner for England said she was seeking clarity from the Home Office “on the specific provisions and what they will mean for children”.
The government said unaccompanied children, those under 18, who arrive on small boats will not be removed to a safe third country until adulthood.
The UN Refugee Agency (UNHCR) has said the Sunak government plan to deport asylum seekers without considering their claims amounted to a “clear breach” of international law.
Senior Tory David Davis and others have pointed out the “real practical difficulties” in locking up thousands of people without any returns agreements outside of an agreement with Albania and the processing deal with Rwanda.
The Home Office is reportedly ready to buy former military bases in Lincolnshire and Essex to detain thousands of migrants.
Mr Sunak suggested that the first deportations to Rwanda could begin this summer. “The Court of Appeal is due to hear the case towards the end of April and we’d get a decision relatively soon after that,” he told reporters on Tuesday.
