An investment bank that changed a report on power privatisation to make it more favourable to the New South Wales Government was "clearly given some orders by people in the Liberal Party," Opposition Leader Luke Foley says.

But Premier Mike Baird said investment bank UBS was already aware of problems with the report and was planning to amend it before it was contacted by the Government.

New South Wales Labor has seized on the report, by investment bank UBS, that says leasing the state's electricity assets will hurt the budget over the long term despite providing benefits for the state.

The report's initial title, "Bad for the budget, good for the state", was sent to clients on Tuesday and later reissued with the amended title "good for the state".

Newspapers have reported the analysis by the bank, which is backing the privatisation plan, was revised after issues were raised by "clients".

The reissued report also included new material on the benefits of the privatisation proposal.

UBS is reportedly advising the Coalition Government on its plan to partially lease electricity assets to the private sector for 99 years.

Mr Foley said the initial UBS report exposed the truth about how privatisation would hurt the state's budget, with the budget bottom line projected to weaken as revenue from power assets fell and infrastructure spending increased.

"I think it's funny that these cheerleaders for the sale, after a refreshing moment of candour, were clearly given some orders by people in the Liberal Party to revise their report if they want a cut of the privatisation action," he said.

Asked if the Government pressured UBS to change the report, NSW Treasurer Andrew Constance said: "The point that's been made, and certainly in terms of UBS, is that they didn't consider economic uplift in terms of their initial report."

"But they've provided an addendum."

Later, Mr Baird confirmed the Government contacted UBS about the report but did not direct the bank to change it.

"Not at all - I mean, they did contact them, having seen the report, but they were already aware that they had not taken [into account] any impact in relation to the economic modelling and they were fixing it themselves."

The ABC has attempted to contact UBS for comment.

Mr Constance said the initial report did not consider all relevant factors, including how asset leasing would lead to the generation of 122,000 jobs.

"UBS didn't factor in the enormous economic uplift and the revenue flow to government through stamp duty, GST and payroll tax," Mr Constance said.

"We are going to see a $300 billion economic uplift to the state as a result of the transaction in the years ahead because we are building congestion-busting infrastructure designed to strengthen the state economy, which is currently experiencing a $500 billion economic lag because of congestion."

But Mr Foley maintained the proposal to privatise power assets did not make sense.

"[NSW Premier Mike] Baird's policy is the equivalent of a worker retiring and taking his or her super in a lump sum to buy a big Ferrari and then not having the funds to live on," he said.

Mr Constance also attacked Mr Foley over comments he made about a Frontier Economics report on the asset leasing plan.

During an ABC TV leaders debate, Mr Foley said the report showed states with publicly-owned power networks had cheaper electricity prices than those with privately-owned networks.

"A Frontier Economics report ... revealed that the cost of electricity per unit is lower in NSW and Queensland, where the networks are publicly owned, than in Victoria and South Australia where they are privately-owned - that is an 'apples with apples' comparison," Mr Foley said in last Friday's debate.

Frontier Economics refute the comment, with CEO Danny Price saying the report "showed the opposite to what Mr Foley implied".

"In comparing the price performance of privatised and government owned networks, Mr Foley has confused changes in prices with price levels," a Frontier Economics statement said.

Mr Constance said Mr Foley had misled the community.

"Frontier Economics have now had to come out, denounce Mr Foley for misrepresenting their report," Mr Constance said.

The state election will be held on March 28.