A prime parcel of government-owned land in inner-city Sydney is to be sold off to private developers with no requirement for any social or affordable housing to be built.

The site on Parramatta Road in Camperdown is just 20 minutes from the CBD and sits on a major transport corridor with a bus stop right outside.

Opposition parties have accused the government of breaching a key election commitment.

Labor went into last year's election pledging that any development on public land would subject to an affordable housing quota.

"Any properties built on surplus government land will be subject to Labor's mandatory requirement for 30 per cent of dwellings to be used for social, affordable and universal housing," the party stated in its Fresh Start Plan election manifesto.

"It is a broken promise," Greens MP Kobi Shetty said.

"We know that they promised an anti-privatisation agenda and that they were going to ensure that every piece of public land had affordable housing on it.

Land vacant for two years

Perched on the southern boundary of Ms Shetty's electorate, the land was compulsorily acquired by the government as a dive site for the construction of a WestConnex tunnel.

For the last two years, it's been a vacant lot, secured behind a padlocked gate.

With the Royal Prince Alfred Hospital just around the corner, Ms Shetty said it offered a rare opportunity to build desperately needed affordable housing for key workers in the inner city.

"We can't have a situation where we're continuing to have nurses and teachers being priced out of the neighbourhoods that they work in and making it harder and harder for them to live in the city."

The local MP was initially excited to hear Labor's announcement this week that 100 homes would be built on the lot.

But her excitement soon evaporated when she learnt more of the detail.

"We understand that they're entirely going to be market properties. So all private development, no social or affordable housing at all on this site," Ms Shetty said.

"It's incredibly disappointing."

Last month, the Minns government announced that it would build up to 30,000 homes on surplus government land over the next four years.

The Camperdown site was among the first four parcels of public land earmarked for development.

No plans for social housing

Housing Minister Rose Jackson confirmed that there were no plans to build social and affordable housing on that particular piece of public land.

"The consistent advice government has received since taking office is that imposing a 30 per cent target on each site would deliver less social and affordable housing, less housing overall, and would do so at significantly greater cost," Ms Jackson said.

"Our target to provide an uplift of social and affordable housing remains the same – but we must have a responsible approach to delivery.

"This will ensure we can get shovels in the ground and a roof over peoples head sooner."

She said the government's target of 30 per cent social and affordable housing would still be delivered across the program as a whole.

"The harsh reality is that people are doing it tough, we need more homes as soon as we can get them," she said.

'Breaking election promise'

The Opposition's housing spokesman Scott Farlow said it was "a clear breach" of the government's pre-election promise.

"The government made a very clear commitment that all parcels that were a result of their land audit would have 30 per cent minimum social and affordable housing on them, " he said.

"The government said every single site. They didn't talk about it being part of the plan overall."

Mr Farlow said the sale of the site to a private developer was in breach of another government's promise not to sell off public assets.

"When we have the sale of public land, it's right that the government should have certain expectations about what should be done on that public land," he said.

"And it is right that social and affordable housing should be part of that component and that is what the people of NSW elected this government to do."

Shortage of affordable rentals

Nicole Gurran, professor of urban and regional planning at the University of Sydney, said the shortage of affordable rental housing in Sydney had reached crisis point.

"We know key workers like nurses, police, teachers in particular, need to be able to live near the communities that they serve," Professor Gurran said.

"When they can't find affordable housing near their work, it's particularly difficult."

She welcomed the government's plan to boost the supply of social and affordable housing.

"They're on the right track by identifying government land and by increasing the investment in social and affordable housing," she said.

She would like to see affordable housing targets on all developments, both public and private.

"The best approach is simply to require property developers to include a proportion of affordable housing as part of all developments," Professor Gurran said.

"Cities like London, for instance, that have similar affordability pressures to Sydney, now require that 50 per cent of homes, particularly on government sites, be affordable.

"It's certainly an aspiration that we should be moving towards in Sydney."