The NSW government's proposed new development levies in the Hunter and the Illawarra will need to be closely scrutinised, according to property development industry group the Urban Taskforce.

Last week the government announced that it will be proposing a $8,800 levy on new homes in the Lower Hunter and a $6,200 levy on new homes in the southern Illawarra. The government's also proposing a $42,100 levy on each hectare of new Lower Hunter industrial land, and a $29,000 levy on each hectare of Illawarra industrial land.

The Urban Taskforce's chief executive, Aaron Gadiel, said the full details of the plan have not yet been released and apparently will not be made public until Friday this week.

"The industry is always nervous when a government starts talking about new taxes," Mr Gadiel said.

"Some development projects will clearly be more expensive, as a result of this charge.

"However, other projects may face lower costs, because the government says it will remove the need for site-by-site negotiation of levies.

"We'll have to carry out a thorough analysis to test the validity of this claim." Mr Gadiel said that the specifics of the proposal were not yet publicly available.

He adds: "We'll need to consider if key infrastructure upgrades, crucial for future urban growth, have been left out of the plans, or have been postponed.

"If the timely delivery of new infrastructure is not guaranteed, new housing and workplaces may have to carry the cost of this levy as well as bearing the burden of additional negotiated contributions.

"Right now, the jury's out, because the government won't release the details for at least another week."