Suella Braverman has said she will vote against the Government’s Rwanda Bill next week if there are “no improvements”.
The sacked home secretary said she was “trying to avoid a catastrophe of failing to deliver on this pledge” ahead of the key vote next week.
It comes as the Prime Minister is braced for a Commons showdown over his Rwanda plan.
Right wing Tory MPs are gearing up for a parliamentary battle after warning Mr Sunak his Safety of Rwanda (Asylum and Immigration) Bill will not work unless it is significantly beefed up.
Dozens are backing amendments to the proposed legislation aimed at effectively ignoring international law and severely limiting individual migrants’ ability to resist being put on a flight to Kigali.
Former justice secretary Robert Buckland, part of One Nation group of centrist Tories, has also put forward a bid to remove clauses which declare Rwanda a safe country, disapply human rights laws and force courts to disregard some European Court of Human Rights rulings ahead of the Bill being scrutinised again by MPs on Tuesday and Wednesday.
Repeating her criticism of the Bill, Ms Braverman said it was “fundamentally fatally flawed” and the amendments were being tabled in a bid to “fix” it.
In the interview with GB News, she said: “What we want to see if we want to stop the boats is regular flights taking off to Rwanda with large numbers of passengers. A token flight with a handful of people on them on it is not going to stop the boats, we need an effective deterrent…
“I’m only going to support a Bill that works. As currently drafted, this Bill does not work. And if there are no improvements to it, I will have to vote against it, I’m afraid. I’m sent to Parliament to vote for things, to be for things or to be against them, not to sit on the fence…
“It’s absolutely essential that we deliver on this pledge to stop the boats.”
No Tories opposed the Bill in an earlier vote last month with rebels, including Ms Braverman, deciding to abstain.
She said there were more than 50 Conservative MPs who had publicly put their names to amendments and who “share our concerns” while also claiming there were a “high number of ministers” who had “grave reservations about this Bill”, adding: “I actually haven’t spoken to many ministers who genuinely believe that this Bill is going to work.
“Privately, under their breath they say to me, we know this Bill won’t work.”
It was “absolutely clear” the Bill would not work, she said, adding: “The Government’s own lawyers themselves have admitted that.”
Robert Jenrick, who resigned as immigration minister over the Bill, also reiterated his position, telling the BBC’s Newscast podcast: “It’s my strong view that this Bill doesn’t work, it doesn’t create that deterrent effect and so we need to improve it.”
Many politicians are “too squeamish” to tackle the subject of immigration and are “worried about being accused of racism or of being uncompassionate” which was “letting the public down”, he added.
Mr Sunak has said he would welcome “bright ideas” on how to improve the Bill, but has previously insisted it already strikes the right balance, with Downing Street saying all amendments would be considered.
It comes as MPs called on the Government to allow a Commons debate on its accompanying treaty with Rwanda.
The Home Affairs Committee said the agreement, signed by Home Secretary James Cleverly during a trip to the country’s capital Kigali last month, will be of “significant legal and political importance” and MPs should be given parliamentary time to “reach a view on whether it should be ratified”.
The fresh treaty was part of Mr Sunak’s goal of making the plan to send migrants to Rwanda legally watertight after the Supreme Court ruled the policy was unlawful.
It needs to be ratified by both the UK and Rwandan parliaments to make it internationally binding.
The scheme has cost £240 million so far, with a further £50 million committed for next year, but so far not a single asylum seeker has been sent to Rwanda due to the legal challenges.
In other developments, documents published in the run up to the Commons vote contained an updated Home Office assessment which “acknowledges that while Rwanda is now a relatively peaceful country with respect for the rule of law, there are nevertheless issues with its human rights record around political opposition to the current regime, dissent and free speech.”
Meanwhile Burundi announced it was closing its border with Rwanda, suspending diplomatic ties and deporting its citizens as it accused its neighbour of backing rebel groups who have carried out attacks.
The Rwandan government has previously denied supporting the RED-Tabara, which Burundi considers a terror group.