The NSW opposition has accused Premier Mike Baird of overestimating the proceeds of a partial sale of the state's electricity assets.
Shadow Treasurer Michael Daley said investment bank UBS's assessment of the value of a potential sale of the state's electricity poles and wires was $18 billion, instead of the government's $20 billion.
He said Mr Baird had been announcing more uncosted infrastructure projects despite UBS's assessment.
"Mr Baird's response to UBS advice is to announce more projects - more unfunded, more uncosted projects that might be built in the next 10 years or not," he said.
"Mike Baird is starting to make this stuff up on the run."
A spokesman for Mr Baird said the government figures were calculated by Treasury and included $13 billion from the net proceeds of the sale and $2 billion from the federal government's proposed incentive payment for selling state assets.
It also includes $5 billion in accumulated interest in the NSW Restart fund in which the government will invest the proceeds of the sale.
He said the government stood by the figures and would not comment on the UBS report.
The NSW government announced this week it will conduct feasibility studies into tunnels under Military Road and the Spit Bridge, in Sydney's north, and the north and south extensions of WestConnex.
The budget could also include plans for an above-ground Bus Rapid Transit (BRT) system linking the northern beaches to the CBD.
Mr Daley said NSW would lose money in the long term if the poles and wires were sold, as they produce regular income for the state.
"The poles and wires return a massive dividend to government year on year," he said.
"They have been well invested in, they are a monopoly, a rolled-gold dividend producing asset for the people of NSW."
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