A former Immigration Minister has expressed "absolute horror" over Rishi Sunak's Illegal Migration bill, saying she will not vote for the legislation.
The Tory MP Caroline Nokes said she could not see how the proposals would act as a "deterrent" to those making the perilous crossing across the Channel.
It comes as MPs gear up for the first vote on the legislation since it was introduced by the Home Secretary Suella Braverman last week in the Commons.
She said those who enter the UK via illegal routes would be detained without bail or judicial review before being deported - and blocked from returning.
But in a sign of the unease over the plans, Ms Nokes became the first Tory MP to rally against the legislation. "I've made clear to my whip, I can't vote for this," she said.
"I didn't vote for the last one, I won't be voting for this one".
"I might be an outlier in my party but I think we have an absolute duty to treat people humanely to keep people safe. I have absolute horror at the prospect."
Providing an example on Times Radio, she said: "An Afghan female MP who has come here under the very limited resettlement schemes is treated very humanely and given the right to work immediately.
"And yet if when an Afghan female MP were to pitch up on the beaches of Dover we'd send her to Rwanda would we? I just think that is wrong."
The senior Tory MP, who now chairs the women and equalities committee, said she had a "range of anxieties" over the legislation that Mr Sunak has claimed will "stop the boats".
She added: "I am deeply troubled at the prospect of a policy which seeks to criminalise children, pregnant women, families and remove them to Rwanda.
"I didn't vote for the last nationality and borders bill, this hasn't achieved its aim in reducing crossings. In fact, we've seen them increase, and I fail to see what this legislation is going to do to act as a deterrent".
Later in the day the Conservative MP Chris Skidmore also said he will not vote for the Illegal Migration Bill when it goes to the Commons for its second reading later on Monday.
The backbencher, who is standing down at the next general election, tweeted: "I am not prepared to break international law or the human rights conventions that the UK has had a proud history of playing a leading role in establishing.
"I will not be voting for the bill tonight."
Last week the plans were widely condemned and the UN Refugee Agency said it was "profoundly concerned".
They said in a statement: "The legislation, if passed, would amount to an asylum ban - extinguishing the right to seek refugee protection in the United Kingdom for those who arrive irregularly, no matter how genuine and compelling their claim may be, and with no consideration of their individual circumstances."
The body added: "The effect of the bill (in this form) would be to deny protection to many asylum-seekers in need of safety and protection, and even deny them the opportunity to put forward their case.
"This would be a clear breach of the Refugee Convention and would undermine a long standing, humanitarian tradition of which the British people are rightly proud."
