Proposals to extend a cramped inner city primary school have been mothballed because of confusion over statistics projecting school places – prompting one school governor to resign.

Anderton Park Primary School, in Balsall Heath, was to expand as part of a programme to create 6,000 new primary places to cope with Birmingham’s climbing birth rate.

But the city council, which had granted planning permsion for the building, has now stopped the expansion, claiming “inaccurate forecasting” of birth rates in Sparkbrook and Washwood Heath by the Office of National Statistics (ONS). But the ONS denied the charge and said it does not even produce birth forecasts.

The scheme to extend and adapt the listed school to accommodate an extra 210 pupils is now on hold after it was found that fewer places were needed than first thought.

Planning permission had originally been granted by the council’s planning committee after a knife-edge vote but pupils now face being taught in temporary classrooms.

Parent and governor Zaman Khan, a father-of-four who handed in his resignation aftera governor’s meeting, said: “It feels like all this hard work has been for nothing. This has been a complete and utter waste of public money. I want to know at what point the council knew the figure wasn’t right. It’s not just a waste of money – it has taken time and a lot of futures will be affected by this.”

Under the council’s Additional Primary Places programme, the school had been due to increase admissions from 90 to 120 reception class pupils per year. Architects had submitted plans for eight classrooms on the first floor of the Victorian building by expanding roof spaces and reclaiming staff areas, which would have needed rubber stamping by the Government before building work could begin.

At a planning committee meeting on October 10, Labour committee members backed neighbouring residents who claimed the school was already too large for the site and caused traffic congestion.

Mr Khan added that the school had to resort to teaching pupils in the sports hall due to lack of space, but the council has pledged to build four temporary classrooms as an “interim solution”.

A Birmingham City Council spokesman said continuing with the planned expansion of the school was “no longer viable in the long-term”, but said it would work with the school to get final planning approval in case the scheme was needed in the near future.

The spokesman said: “Like many local authorities, Birmingham relies on data from the ONS as the basis for primary school number projections. When Anderton Park was included in the Additional Primary Places Programme in late 2009, reliable data was only available up to September 2012, but this showed a significant increase in births over the previous five years for Sparkbrook.

However, data released this year showed a significant drop in births in Sparkbrook. In the immediate area around the school – a one-mile radius – the number of births was 208 fewer last year than in 2009 – an extraordinary reduction equivalent to seven full infant classes in just one year.”

A spokesman for the ONS said: “ONS does not in fact produce birth forecasts or projections by ward – although it does produce figures for live births by ward for past years. Therefore we are not certain what figures the city council is referring to or where they come from.”