Greens MP John Kaye says the NSW government ports sell-off privatises the profits and dumps the risks onto taxpayers.
The proposed privatisation, which passed the Lower House on Wednesday night, allows the lease of state-owned Port Botany and Port Kembla, either as separate entities or together.
Proceeds from the transaction will be invested in the government's infrastructure fund, Restart NSW.
Greens NSW MP John Kaye on Thursday said the NSW government's privatisation agenda was about to claim another scalp.
'It will not just rob the state of vital long-term income streams and threaten public-sector workers' jobs,' he said in a statement.
'The O'Farrell government's legislation also hands Treasurer Mike Baird the power to sell off valuable public assets while retaining responsibility for any of the ports' liabilities with NSW taxpayers.'
Mr Kaye said that under the ports sell-off legislation any failure or accident could land the state with a bill to compensate the private owners for lost income.
'All of us will end up paying for the massive profits of the corporations,' he said.
Earlier on Thursday, Mr Baird said the transaction was critical to the future of the state and the ports, and a private lessee would bring many benefits, including greater access to capital and specialist infrastructure expertise to develop the facilities.
The bill is expected to be debated in the NSW Upper House next week.