United Kingdom Prime Minister Boris Johnson's government suffered a fourth defeat on its Brexit legislation when members of Parliament's upper chamber voted to ensure protections for child refugees after Brexit.

Johnson's Conservative Party won a large majority in the lower chamber, the House of Commons, in a December 12 election. Earlier this month, legislators there quickly approved the legislation needed to ratify his exit deal with Brussels.

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But the House of Lords, where Johnson's government does not have a majority, made three changes to the legislation on Monday, including over the rights of European Union citizens after Brexit.

On Tuesday, the Lords voted 300 to 220 to ensure unaccompanied child refugees can continue to be reunited with family members in the UK, a promise made by Johnson's predecessor Theresa May but stripped from his legislation.

Johnson's spokesman said the government would seek to overturn the changes made to the Brexit legislation when the bill returns to the House of Commons later this week.

Earlier this week, Lord Alf Dubs, an opposition Labour Party peer who fled to the UK as a child to escape the Nazis, and who proposed the change to the bill, told Al Jazeera that child refugees should not become collateral damage of Brexit negotiations.

"I can see no moral justification for the removal of my amendment from the withdrawal agreement bill. As we leave the EU, we cannot abandon our compassion and humanity," he said.