Government pressure to increase the amount of housing in the West Midlands by 575,000 dwellings is likely to be a serious over-estimate of demand for new accommodation, council leaders have warned.
Birmingham, the Black County and Solihull would see its housing stock soar by almost a quarter if provisional figures produced by Whitehall were approved.
Across the region as a whole 575,000 new dwellings are being proposed, an increase of 27 per cent on existing provision.
The biggest housing push since the Second World War is required to meet demographic change, longevity and significant growth in the number of people living alone, according to Ministers.
Local authorities fear that the target for new build, which would have to be met by 2026, could not be delivered solely on brownfield land in urban areas and would put sensitive rural and green belt sites at risk.
They are also questioning whether the construction industry would be capable of building so many homes within the timescale set out.
A report to the West Midlands planning and transportation sub-committee warns of "many major sources of uncertainty" in the projections, which have been the subject of protests across the country and are already being reviewed by the Department of Communities and Local Government and the Office of National Statistics.
Preliminary results of research commissioned by Birmingham City Council suggests that Government estimates for the number of new households required between 2001 and 2026 across the West Midlands are over-estimated.
Birmingham would have to find space for 92,000 new dwellings, taking the total housing stock to just under 500,000, if the provisional figures are rubber-stamped.
The city council believes that a smaller increase, of about 83,000, would reflect true demand and be deliverable.
There is also concern that the market-led approach to new housing is unlikely to satisfy Birmingham's need for low-cost alternatives, in a city where 27 per cent of the stock is social housing.
Ken Hardeman, the Birmingham cabinet member for regeneration, said he feared the Government had "got its sums wrong" and predicted that the 92,000 figure would force the council to look toward developing on the green belt.
Coun Hardeman (Con Brandwood) added: "The reality is, whatever targets are set by the Government, can we deliver?
"The only way we can deliver is if we know we have the land and the resources to enable us to meet the target that has been set. If you start imposing false targets, we would have to look at where we are going to put the housing and that suggests using the green belt."
In Coventry, the number of homes would increase by more than a third with 44,000 new dwellings planned. The largest increase in the West Midlands is proposed for Telford & Wrekin, with a 56 per cent jump.
The Government is sticking by its estimates and has warned local authorities that "convincing evidence" will be required as to why the proposed levels of housing provision could not be met.
Pressure on councils to meet Government housing targets is bound to lead to more development in the countryside and on green belt land, according to the Campaign to Protect Rural England. Builders would swoop to acquire rural sites, where they could make higher profits, leaving councils unable to sell brownfield land, it warned.
The CPRE believes the West Midlands can cope with no more than 400,000 new homes over a 25-year period.