The Prime Minister will introduce his new Withdrawal Agreement Bill (WAB) today in a special Commons sitting as he hopes to pass is in time to leave the EU next month.
But shadow Brexit Secretary, Sir Keir Starmer, has accused him of watering down previously agreed measures designed to protect child refugees.
It meant the Government was legally obliged to seek an agreement with the EU that would allow unaccompanied minors to join family members in the UK if they are in any other member state.
But, as Sir Keir pointed out, the updated legislation sets out that the Government merely has to "make a statement" on the issue, rather than commit to negotiating such an agreement.
"The requirement obliges a Minister of the Crown to make a single statement to Parliament within two months of Royal Assent setting out the Government's policy intentions in respect of any future arrangements with the EU in relation to family reunification for unaccompanied children seeking international protection in the UK or EU."
Sir Keir, who is likely to put himself forward to take over from Jeremy Corbyn as the next Labour leader, tweeted about the legislation change.
He said: "During the last Parliament, Labour's Alf Dubs led the campaign to protect child refugees post-Brexit. The Tories now want to tear up these protections.
"As we leave the European Union, we can’t abandon our values of human rights and internationalisation. Labour must continue to stand up for the most vulnerable people in the world."
A Home Office spokesman said the Government has a "proud record of providing protection to vulnerable children" and insisted this would not change, despite the change in legislation.
They said removing it from the bill would make it easier for the UK to negotiate a deal with the EU.
“The new clause makes clear that supporting the most vulnerable children remains a priority, and does so in a way that will enhance rather than undermine our negotiating position. We are restoring the traditional division of competences between Parliament and Government when it comes to negotiations.”