Qld's Labor govt forces voting change

Queensland's Labor government has outfoxed the opposition to ensure it has a major advantage at future elections by reintroducing compulsory preferential voting.

The Liberal National Party (LNP) earlier this week blindsided the government by introducing and pushing through a move to increase the number of state MPs from 89 to 93.

That bill was passed in the hung parliament on Thursday with the support of Labor defector Rob Pyne.

But Labor immediately returned fire, tacking an amendment onto the bill to reintroduce compulsory preferential voting, meaning Queenslanders will be forced to number every box on their ballot papers.

The move, which will significantly benefit Labor and minor parties at the expense of the LNP, was passed with the backing of the state's four crossbenchers on Thursday night.

If the voting system was in place at last year's election, Labor would likely have gained enough seats through Greens and minor party preferences to govern in its own right, instead of needing to rely on cross bench support in a minority government.

"On my estimates Labor would have won an extra 9 seats at the 2015 Qld election under full preferential voting," ABC election analyst Antony Green tweeted on Thursday night.

Attorney-General Yvette D'Ath denied the government's motive was political, insisting the amendments sought to reduce the number of informal votes.

Unsurprisingly, LNP MPs were ropeable, with dozens lining up to speak against the amendments to filibuster while the LNP's leadership team were negotiating with crossbenchers.

"Today we have seen democracy die," LNP MP Trevor Watts said, while his colleagues used descriptors like "appalling", "payback politics" and "sneaky".

LNP MP Ros Bates said: "This is the most disingenuous act of corruption and bastardry that I have ever witnessed in this parliament in the almost eight years since I have been a member."

Optional preferential voting has been used in Queensland state elections since 1992, giving voters the option of marking one or all of the boxes on the ballot paper.

Earlier, Mr Pyne offered his support for the bill to increase the number of MPs, referring to it as a "step forward for Queensland".

"This is about ensuring improved access, representation and restoring democracy to the Queensland people," he said.

Queensland MP numbers haven't increased since 1986, when they were boosted from 82 to 89.

The changes are expected to come into effect after the next election, due in early 2018.