The Home Office turned down repeated offers from fostering agencies that would have allowed up to 100 child refugees a week to be given sanctuary in Britain, according to the chief executive of the UK’s largest fostering and adoption charity.

The revelation further contradicts the government’s explanation for winding down the Dubs scheme. Ministers defended the heavily criticised decision by claiming that councils had no more spaces to accommodate child refugees from Europe. Yet it has emerged that, as far back as September 2015, Home Office officials met with fostering agencies to discuss the placement of Syrian child refugees, unaccompanied minors and the working of the Dubs scheme. The move would have provided instant extra capacity for Britain to accept children and could have operated alongside or instead of councils offering spaces for unaccompanied minors, an option that would have enabled the government to move towards its commitment to helping unaccompanied minors.

About 3,000 children were originally expected to come to the UK under the Dubs scheme, but the home secretary, Amber Rudd, has limited the number to 350, saying councils do not have enough capacity. Some local authorities have since come forward to say they were not consulted properly and that when they offered to take children they were either ignored or rejected by the Home Office.

Fresh details of the government’s belated acceptance of child refugees from the Calais camp last October reveal that the Home Office’s response was so chaotic and badly planned, some child refugees were allegedly forced to wait for hours without food and water after arriving in the UK – a claim the Home Office said was “completely wrong”.

Details of the fostering offer to house unaccompanied minors have been revealed by Andy Elvin, chief executive of Tact Care, the UK’s largest fostering and adoption charity, who said that a series of meetings was held involving Home Office officials, the Department for Education and foster organisations between September 2015 and 7 June 2016, which looked at solutions to the transfer of child refugees from Europe.

“Between those two dates we offered on numerous occasions to the Home Office the option of contracting directly with us and other fostering agencies, rather than going straight to local authorities,” Elvin said, whose charity has more than 500 foster carers and adopters across England, Scotland and Wales. “At any given time we could supply 100 to 200 places a week for children between all the independent fostering agencies, including private. The idea was that Dubs would be done over a number of years, for instance if they had planned for 100 a month to come in over a year that could easily be handled. The fact is that we could offer those numbers now, we could still place children now.”

But Elvin said the Home Office declined the proposal, saying the issue was the responsibility of local authorities, a decision used last month by the government to stop accepting the children. A move to require councils in England to identify whether they have spare capacity to house unaccompanied child refugees was narrowly rejected last Tuesday by MPs.

Elvin estimated that the UK’s fostering capacity could accept at least 1,200 refugees over a year, with the capacity sufficient to absorb 100 children a week in an emergency. He said that during May last year – after the former prime minister, David Cameron, told parliament that Britain would accept unaccompanied refugee children under the Dubs scheme from France, Italy and Greece – Tact had a number of meetings with the government offering to instantly accept Dubs children.

The reality was it took five months to accept the first child refugee from the Calais camp under Dubs, and that was two days before the camp’s demolition.

“We were talking to the Department for Education, because they were having meetings with the Home Office, and saying we can offer this fostering capacity now if you want it. They were aware of this throughout, but never engaged with it,” said Elvin. “There was never any planning done and there could have been. For a long time we knew where the children were – they were in Calais. Instead, it was so reactive we had cases where we had young people who were sitting in Home Office buildings, sometimes without been given food and drink for six, seven hours, treated appallingly, while the local authority is told about it that day. It was a fiasco, and children suffered.

A Home Office spokesman maintained that the number of Dubs children was “in line with available local authority capacity. The UK’s doors will remain open to all those who need our protection and we are very grateful for the support that local authorities and the public provide to the asylum system.” Last week’s vote to bring back the Dubs scheme was defeated by 287 votes to 267, with 282 Tory MPs voting against it, dismaying charities such as Safe Passage which have helped child refugees find sanctuary in the UK.