PJ Livesey, a specialist heritage developer, has dropped any social or cheaper homes in its 209-home scheme at the site in Locksway Road, Milton.
A report found that with affordable housing it would make 18.84 per cent profit for the developer – some £12.89m – but a return of at least 20 per cent, £13.69m, was needed.
Instead £2.87m will be handed over to the council as a contribution to public amenities.
Some 179 objections have been raised to the plans, including from council leader Gerald Vernon-Jackson and Milton Neighbourhood Planning Forum.
Cutting down from 84 new-build homes to 58 has led to ‘restricting our ability to provide affordable housing,’ PJ Livesey said.
Labour councillor Cal Corkery said: ‘This is the latest local example of wealthy property developers pleading poverty when it comes to providing affordable housing.
‘It's even more outrageous when you consider this is publicly-owned land.
‘The Tories in Westminster created this legal loophole for their developer mates to exploit but local councils still have a responsibility to secure new affordable housing for local people through the planning system.’
A decision on the plans have been pushed back until after the election.
Homes England has a separate 107-home planning bid for a section of the site set to be considered by councillors at a meeting on Tuesday.
Cllr Vernon-Jackson said the decision on PJ Livesey’s plans should be considered with the Homes England bid.
‘It’s the basic fundamental bit of planning that you try to do planning together and you don’t do it piecemeal otherwise you have one decision that could have a huge (effect) on another part,’ he said.
Cllr Vernon-Jackson said the council chief executive took the decision as no political decisions could be made close to the election.
Portsmouth Conservative group leader Donna Jones said: ‘I’m completely perplexed as to why this is not coming forward to the March or April committee.
She added she was ‘extremely concerned’ and added: ‘It would seem appropriate for an investigation to be carried out.’
PJ Livesey, whose purchase of the site is dependent on planning permission, said the NHS is spending £1.6m a year on maintenance at the site.
James Woodmansee, a director, said: ‘We have significantly reduced the number of new build homes from when the site was marketed down to just 58 at the request of local councillors and local residents and this impacts on affordable housing.’
The existing main hospital and mortuary will be converted into 151 homes, ranging from one-bed flats to four-bed houses. New builds would include five-bed homes that could sell for up to £640,000.
Around 129 trees would be planted, and new pathways and a cycle path installed. St James Chapel could be put to community use, but this would reduce parking.
The cricket pitch and pavilion would be kept and given on a long lease to the club.
Mr Woodmansee said: ‘Our proposal to convert the buildings to residential use would preserve their history and character and help the city meet its housing targets.
‘Selling the site will not only raise crucial funds for the NHS but save on-going maintenance costs of £1.6m per year, money which could be invested in local healthcare in Portsmouth.
‘The NHS and ourselves and Historic England are keen to see these plans progress.’
NHS Property Services was approached to confirm the £1.6m maintenance spend but no reply was given to The News.
The viability report done for the developer said the level of profit was ‘below an acceptable minimum,’ and suggests a reduction in planning contributions could also help.