The NSW Education Secretary has been grilled over why she did not tell her minister about the impending shutdown of Sydney's rail network.
Georgina Harrisson has told a NSW budget estimates hearing she was sent a request by Transport for NSW asking her to outline how major disruption on the network would affect the department.
The staffer was defended by Education Minister Sarah Mitchell on Wednesday, who labelled questions about why her staffer did not brief her as a "conspiracy theory".
Ms Harrisson told the hearing her department told Transport the disruption would be "significant".
Labor MLC Courtney Houssos asked why the potential disruption of the rail network was not raised with the minister.
"That was not something I felt needed political engagement," Ms Harrisson said.
"We were asked, operationally, what is the impact on schools of potential disruption to the railways? We provided that advice."
She could not remember if she was formally notified of the shutdown of the rail network before the decision was made to cancel services on February 21, when 55,000 students were unable to travel to school.
Ms Mitchell told the budget estimates committee her officials had done what was required of them by providing advice to another department.
"I can appreciate you trying to paint a bit of a conspiracy theory here but the reality was that the department was asked to provide advice to another agency," she said. "They did that.
"If you want to question why those questions were sought from another agency you need to direct those questions to the agency that sought the information from the department of education."
Ms Mitchell said she was not aware the train network would be shut down and only became aware from news reports after services had already been halted.
Labor MLC Anthony D'Adam asked Ms Harrisson whether the questions from the transport department had set off "alarm bells".
"At the time we had no indication from the department of transport about the likelihood of the shutdown happening," Ms Harrisson said.
"We responded to the request we were given. We responded to it factually and accurately. The affidavit is in the public domain. We have nothing to hide."
Australian Associated Press
Sign up for our newsletter to stay up to date.