Queensland Opposition Leader Tim Nicholls has promised there will be no forced redundancies within the public service if the Liberal National Party wins the next state election, but the union isn't buying it.

The Queensland Liberal National Party leader released a public service plan on Sunday that "categorically ruled out" any forced redundancies if the party is successful at the next state poll.

But public sector union Together secretary Alex Scott said no one could credibly believe him given his track record as treasurer under the Newman government.

Mr Scott said the sector – which currently has about 200,000 full-time employees – suffered "savage" cuts under the former LNP government.