The NSW corruption watchdog will be given more powers to investigate government ministers, and the ministerial code of conduct will be made the “toughest” in the country, Premier Mike Baird says.

The moves come after damaging revelations this year resulting in the sidelining of nine NSW Liberal MPs, including the dethroning of premier Barry O’Farrell.

·Union calls for national ICAC

Mr Baird announced the changes on Thursday amid the latest allegations made at the Independent Commission Against Corruption (ICAC) about the Liberal Party’s fundraising activities before the 2011 state election.

“It’s a very significant step forward in terms of, I think, ethics in the state,” Mr Baird told a budget estimates hearing.

“It gives you a sense of what I’m trying to achieve as premier of this state.”

Under the changes, which will come into effect on September 20, ministers who “substantially” breach the code of conduct will be open to being found corrupt by the ICAC.

The code of conduct will also prohibit ministers or their staff from pressuring state government agencies into changing their recommendations.

“(This) sets the benchmark for Australia,” Mr Baird said.

“We now have the toughest ministerial code of conduct in the nation, and it’s about time.”

Simon Smith, acting secretary of the Department of Premier and Cabinet, said the changes would allow the ICAC to identify corrupt conduct “much more quickly”.

“(It means) you couldn’t be a corrupt minister for a long time (and would have) less time to make trouble,” he told the hearing.

The new code will also toughen disclosure rules for ministers and their family members, and will ban ministers from holding or acquiring an interest in any company or business, with “limited exceptions”.

The ICAC revelations have so far led to Mr O’Farrell’s demise, forced former Liberal MPs Tim Owen and Andrew Cornwell to quit politics and relegated six other Liberals to the crossbenches.