The NSW government could fully privatise WestConnex despite Premier Gladys Berejiklian previously declaring there were no plans to sell off its remaining stake in the Sydney motorway.

NSW Treasurer Dominic Perrottet on Friday announced a scoping study to determine if the government should retain or trade its 49 per cent share in the toll road.

The study will investigate the options available to the government but Mr Perrottet said a prospective sale wouldn’t proceed without “clear evidence that doing so would be in the best interest of the people of NSW”.

The Berejiklian government sold 51 per cent of the Sydney Motorway Corporation, the group building WestConnex, to Transurban for $9.26 billion in September 2018.

That money has financed the final stage of WestConnex linking the M4 and M5 motorways, other infrastructure projects in western Sydney and a future generations fund which has grown to $11 billion.

Any funds reaped from WestConnex’s potential sale would be used to extend the government’s $97.3 billion infrastructure program, Mr Perrottet said.

Ms Berejiklian last April said a further selldown of the toll road was “not on the agenda” but the state’s unprecedented bushfires and the coronavirus outbreak are likely to damage the budget bottom line.

Ms Berejiklian on Friday denied she had promised to not privatise additional public assets.

“Before the election I was asked, are (we) going to privatise electricity – I said no. Do you have any plans to privatise water – I said no,” Ms Berejiklian told reporters in Sydney.

“I’ve also said on numerous occasions both before and after and during the election time that we will always look at opportunities that are going to improve the life of our citizens, we will always look at innovative ways to do things.”

Any privatisation would be a “financial vehicle” and would not make “one iota of difference to our customers, to our citizens,” Ms Berejiklian said.

She said the additional capital would help the government complete infrastructure projects sooner.

Operational control of WestConnex will revert back to the state government in 2060 regardless of its ownership.

Advisers are expected to report back with their findings in the second half of this year.