A controversial move to merge a crumbling junior school with a neighbouring infant school could cost millions more than repairing the existing site, it has emerged.

Angel Road Junior School in Norwich has been empty since July 2021 after its roof started to collapse, with its pupils taught across its infant school site and in spare classrooms at St Clement's Hill Primary.

The Evolution Academy Trust, which runs the schools, plans to expand Angel Road Infant School to accommodate pupils from both schools on the single site from September. But as details emerge of how much this project might cost, campaigners have hit out at the trust for, what they claim, is a lack of transparency over the project.

The trust has told parents it would cost around £1.8m to bring the building, which is more than 100 years old, back up to code and that it intends to return it to Norfolk County Council.

In information shared with parents, the trust said the expansion would cost in the region of £1m, almost half the amount it would cost to repair the junior school.

However, a report put before its trustee board obtained through the Freedom of Information act has shown that the proposed final cost of the project could exceed £4.7m - more than double the cost of the junior school repairs.

The report included an extensive shopping list of things the expansion could consist of, such as adding several new classrooms, remodelling others and installing a multi-use games arena.

Linsey Holzer, Evolution chief executive, said many of the things listed were "aspirational work" - and the £1m figure was the only amount the trust had approved.

She said: "The first phase of the project that we have allocated funding to and agreed has a budget of around £1m which has been funded from resources within the trust.

"At Angel Road, like other schools, there are many things we would like to develop at the site, for example, an all-weather pitch for community use or a significant new build and these are outlined in further phases of work we would like to achieve.

"We have no funding for these further pieces of work but we work to try and achieve these aspirational plans in our schools by identifying the projects and proactively seeking funding."

The proposals have been heavily criticised by councillors across the political spectrum, with the Trust accused of being secretive over its plans.

Emma Corlett, deputy leader of the Labour group at Norfolk County Council, said: "The situation has been badly handled from the outset and shrouded in secrecy. The Trust has not been up front with parents or straight about the costs of repairs to hand the school back to the council.

"We are yet to see anything that persuades us that the existing school could not - and should not - be repaired and parents must wonder if the agenda the whole way through has been to set up an all-through school on one site."

Alex Catt, Green Party city councillor for the Sewell ward, said: "The closure of the site at Angel Road Junior has been handled badly from the start with poor communication with parents, lack of investment for our children and the community being sidelined.

"We were told that repairs to bring this site up to standard would cost £1.8m, which was the justification for the permanent closure and extension of Angel Road Infant.

"Now that we understand the cost for the extension could be more than double that cost, this begs the question of why the site was closed in the first place.

"The trust needs to urgently explain what the rationale is behind these decisions and how they represent good value for money and long term investment into the education of the city's children."

Meanwhile, John Fisher, Conservative cabinet member for children's services at County Hall, told a full council meeting: "I'm as concerned as local residents are as to what has happened.

"We know the Evolution Trust took the building on when it was in perfectly good condition and we have evidence they have not maintained it as well as we did."