Backbench MPs Nick McBride, Fraser Ellis, Steve Murray and Dan Cregan voted with Labor three times to put off a vote on the Mining Act, arguing it doesn’t strike a “fair” balance between farmers and miners.

Cheered by more than 50 Yorke Peninsula farmers, they voted with Labor to delay a vote until next February, in defiance of Energy and Mining Minister Dan van Holst Pellekaan’s wishes to pass it through the Lower House this week.

The MPs argued the Bill did not do enough to address the power imbalance between farmers and mining companies over access to land. Mr Ellis strongly arguing for landowners to be given a right to veto.

All four had voted for the Bill to be adjourned in a marathon Liberal party room meeting on Monday night, but they were defeated.

Opposition Leader Peter Malinauskas said the vote was “unprecedented” and Mr Marshall had lost control of his own party, just eight months after winning the state election.

“What we’ve just seen is an extraordinary event,” he said.

“Liberal MPs are in open revolt, siding with the Opposition instead of their own Government and Premier. And they didn’t just do it once, they did it three times.”

The Advertiser reported last week that six Lower House MPs had reserved their rights to vote against their Bill, but four were likely to do so.

Mr Murray, a former Liberal Party president before entering parliament at the state election, said it pained him to vote against the Bill.

“It is instinctive for me to support the Liberal Party. Accordingly, it is incredibly difficult for me not to support this Bill, but I am convinced that, in the words of my late father, I am doing the right thing,” he told Parliament.

Mr Murray said he could not support the Bill because it did not address land access issues and a lack of consultation with the farming community over the Bill. “Everyone knows farmers are often preyed upon, predominantly by unscrupulous explorers, as distinct from miners,” he said.

“No-one cares if they do, not enough to actually do anything about it. There are no industry codes and there is little prospect of any censure or court action for perpetrators. It is literally the wild west.”

In a blistering attack on the Bill, Mr Ellis said the Government was “repeating the mistakes of the previous Labor Government” by pushing ahead with the legislation in the middle of the grain harvest.

The Narungga MP said he did not “oppose my party easily” but felt he must because of the discontent in his electorate over the “legitimacy” of consultation with the farming community.

Mr Malinauskas said it was “utterly reasonable” for the Opposition to adjourn a Bill that was almost identical to the one the former government proposed last year because Labor had yet to determine its position on amendments the Government filed on Tuesday.

In a speech to Parliament, Attorney-General Vickie Chapman said it was important to note the Bill would be reviewed to ensure it was operating correctly. She said the proposed Act provided “some protections” around land access but said a right to veto was “not something that we can justifiably accept”.

Mr van Holst Pellekaan and Mr Marshall were contacted for comment.

Under both the current and proposed legislation, farming land is exempt from being accessed by mining firms without permission unless they apply to waive that exemption in court.