Former prime minister John Howard has waded into the Queensland election campaign and lashed Premier Annastacia Palaszczuk over her mixed messages about the Adani coal mine.
The Liberal Party elder statesman visited LNP incumbent Tarnya Smith in her Brisbane electorate of Mount Ommaney on Friday.
Mr Howard said it was not a good idea to support someone like Ms Palaszczuk, who didn't appear to know where she stood on such a "fundamentally important" issue like Adani's Carmichael coal mine.
"The first requirement of effective leadership in politics, whether you're Labor or Liberal or National Party or LNP or whatever, is to know what you believe in and where you stand," he said.
"The problem Annastacia Palaszczuk has is that I don't know where she stands on the Adani mine."
Mr Howard said the premier's views had changed based on where she was in Queensland.
"In one part of the state she's for it, in another part of the state she's sort of against it and in another part of the state (she's) right against it," he said.
"Now that is unimpressive irrespective of what your politics are."
The premier has come under fire during the election campaign over her handling of the Adani issue after she vowed to veto a $1 billion federal taxpayer-funded loan to the mining giant.
She initially said the decision was to avoid the perception of a conflict of interest following revelations her partner Shaun Drabsch worked on the loan application with employer PricewaterhouseCoopers.
But Ms Palaszczuk later said it was to meet a 2015 election commitment.