The Scottish and Welsh governments have written to the UK immigration minister raising concerns about the treatment of unaccompanied child refugees.
The letter criticises "lack of planning and sharing of useful information" in the Dubs resettlement scheme.
Only about 200 children entered the UK under the scheme last year and none has arrived in 2017, the Home Office confirmed last week.
The UK government promised to honour its commitments on refugees.
The so-called "Dubs amendment" was named after campaigner and Labour peer Lord Dubs, who came to the UK as a child refugee before the outbreak of World War Two.
Lord Dubs' amendment required the UK government to provide assistance to a specified number of unaccompanied child refugees, who arrived in Europe with no family connections.
The UK government has agreed to take up to 480 unaccompanied children under the Dubs scheme - but it will then close, with ministers arguing that an open-ended commitment would encourage people trafficking.
But a joint letter from the Scottish Secretary for Equalities, Angela Constance, and her Welsh counterpart Carl Sargeant criticises the way the scheme has been run.
It states: "From the start of the implementation of this scheme, we have struggled with the lack of information that has been forthcoming from those running this operation.
"This continues to be the case and we are aware that only a couple of hundred unaccompanied children have been transferred of the 480 placements identified."
The letter acknowledges the emergency clearance of the Calais refugee camps led to "difficult circumstances" and that the UK government is also facing a legal challenge over the scheme.
It continues: "However, we both feel that overall, the lack of planning and sharing of useful information from coordinators has inhibited our ability to plan ahead."
Immigration Minister Brandon Lewis said the UK government was committed to fulfilling its commitment under the Dubs scheme "as soon as possible" and that other mechanisms were available for helping vulnerable children.
He added: "This is just one aspect of a much wider response. We have committed to resettling 23,000 people directly from regions of conflict and last year we granted protection, or another form of leave, to over 8,000 children.
"We are grateful for the support Scotland and Wales have provided and we have made clear our intention to extend the National Transfer Scheme to the rest of the UK so their local authorities can fully participate.
"We believe the most vulnerable children are in the conflict zone around Syria and best way to help them is by resettling refugees directly from the region. This is how we can stop traffickers and smugglers from exploiting vulnerable people and children."