Reports in The Australian newspaper on Tuesday revealed at least 13 staff members in Mr Stokes' ministerial office had departed in the past 12 months amid claims of bullying by a senior staff member.

Mr Stokes in NSW budget estimates on Tuesday denied Labor MP Adam Searle's allegation he oversaw a hostile workplace environment.

He said it was tantamount to "rumours and smear, based on innuendo".

"I certainly do not support bullying or intimidation, including via anonymous smear campaigns in newspapers," Mr Stokes said.

"There is a great culture, supportive of one another, ably led. They are professional, competent ... they have my support."

Mr Stokes said he had about 10 ministerial staff at any one time and there was no single reason for what Mr Searle labelled a "mass exodus" of staff.

Mr Searle also told estimates only two members of Mr Stokes' ministerial staff had remained in their position over the long term.

Five of the 13 departed staff members wound up at the Department of Planning, Industry and Environment in the public service, Mr Searle said.

Mr Stokes did not disclose if staff had directly approached him with bullying allegations, nor if he had discussed the issue with Premier Gladys Berejiklian.

"I have a statutory obligation to provide a safe workplace for all people who work for me. I take that obligation very seriously," Mr Stokes said.

"I will not tolerate bullying in my office ... sure, from time to time, there are stresses as there are in any workplace. But the people who work with me and who support my efforts, I absolutely support them.

"I'd lie in front of a bulldozer for any one of them."

Australian Associated Press