Premier Gladys Berejiklian would not be drawn on when the significantly delayed Sydney light rail project would be finished, as the government faces a legal battle with the Spanish subcontractor building it.

When asked in question time on Tuesday about the delays, Ms Berejiklian did not provide details around when the project connecting the CBD to the eastern suburbs would be completed. It was due to be finished in 2019.

The state government is facing a legal battle over the light rail project.

But she did stress that NSW would "not be held to ransom" by the Spanish subcontractors who are reportedly demanding an extra $1.2 billion from the government.

Spanish builder Acciona, subcontracted by ALTRAC, is taking Transport for NSW to court, with the dispute listed to appear in the NSW Supreme Court on Friday.