Former ministers are expected to pile more pressure on the government to rethink plans to allow the detention of families with children as part of the illegal migration bill. The former justice secretary Robert Buckland said he was uncomfortable with the plan to reduce small boat crossings that would in effect reverse a ban on child detention implemented under David Cameron. Other ministers are expected to highlight concerns in the House of Commons on Monday about the possibility of detaining children in migrant centres. Several senior Tories, including the former home secretary and immigration hardliner Priti Patel, are expected to raise their concerns about the treatment of children who arrive in the UK with their parents. The bill will have its second reading in the Commons on Monday where rebel MPs suggested they would not vote down its passage but seek reassurances as it goes through the parliamentary stages. “This is a classic example of something the Lords will amend if we don’t,” one former minister said. “It’s hard to see how [the government] lets it get to that stage. It would be foolish to engage in a prolonged battle on this.” The Home Office has admitted that the change could mean families are detained, saying it was crucial people-smugglers were not incentivised to send children across with adults or target families. The home secretary, Suella Braverman, is said to have made it clear to concerned MPs that unaccompanied children would be exempt from detention, even though there are technical provisions in the bill for them to be detained if they arrive from countries deemed to be safe, such as Albania. The chancellor, Jeremy Hunt, sidestepped the question when speaking on the BBC on Sunday morning, saying “the home secretary has made clear that we are going to treat children differently under these arrangements” but declining to say if he was in favour of the possible detentions. Former Home Office minister Caroline Nokes told Times Radio she will not vote for the new bill. She said: “I’ve made that clear to my whip, I can’t vote for this. 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.” Buckland told GB News he was uncomfortable with the change of plans and that there would need to be a rethink by the government. “I agree with Priti [Patel] on this. It’s been our policy as a government not to treat children that inhumane way,” he said. “Now, I absolutely understand that there’s a concern that somehow children and women are being used as a sort of ‘way in’ for unscrupulous people to come into this country. But I think we’ve really got to think carefully before using detention centres or places of incarceration for children. I just don’t think that’s right. And I hope that in the course of the debate, we can look at that and refine the approach.” He said he expected significant scrutiny of the policy when the bill reaches the Commons on Monday. “I think we need to look very carefully as parliamentarians at exactly what they’re saying. It was made clear to me and I think rightly so, that you have to have exemptions for children and the very ill,” he said. “If you have a total blanket policy, I think any court is going to have a problem with that. And there are exemptions in there, which is why the government is confident that they are working within international law obligations.” MPs are understood to have been seeking reassurances from No 10 and the Home Office this weekend. One former minister told the Observer that the changes to rules on children “make me sick just to mention” and would have to be modified. “God knows what happens around safeguarding, and access to medical treatment,” the former minister said. “Could [children] be removed from the country without parental or family consent? The mind boggles. I think these concerns will start to come out in the coming days and weeks.” The ban on child detention was passed into law in 2014 by the then home secretary, Theresa May. Sources close to May said they were unaware of any plans by her to intervene.