The Liberals and Nationals also handed their draft policy to the NSW Farmers Association to amend - but only after changes made by the NSW Minerals Council were included in the document.

Two draft versions of the land use policy passed to the Herald show the minerals council insisted certain anti-mining lines be removed.

A draft Coalition commitment to ''improve monitoring and compliance'' for any mining project on agricultural land was twice deleted from the ''strategic regional land use planning policy'' document. The line does not appear in a later policy document given to the farmers association for comment.

The manipulation of election policy by miners is bound to call into question Barry O'Farrell's recent conversion to conservation and the environment. Less than a fortnight ago the Opposition Leader said he would create a new national park south of Sydney if he wins office in March.

It will also stir bad blood between miners and farmers in resource-rich areas of NSW where landowners, particularly in areas like the Liverpool Plains, are concerned about the rapid growth of coal and coal seam gas projects and exploration.

Mistrust between farmers and miners has even descended into industry whispers about why the opposition industry spokesman, Duncan Gay, snubbed the farmers association's Christmas drinks last month but attended the minerals council's soiree.

The documents show the miners are desperate to play down tensions, asking for the removal of a reference to growth in the industry as increasing ''land use conflict''. The council changed that to ''seeing expansion of these industries on to high value agriculture land''.

The council also asked for any reference to ''water resources'' and the potential impacts of mining on them to be removed, preferring the term ''precious environmental assets''.

Miners have had to defend coal seam gas extraction, which can damage water tables particularly when the so-called ''fracking'' or rock fracturing technique is used.

The document reveals plans by the Coalition to establish an office of agricultural sustainability and food security, reporting directly to the premier. Farmers have been calling for the office and a halt to all mining projects until detailed assessment of land use is conducted by a new government.

The minerals council is against the idea, noting that it hadn't been ''fully thought through, including how the office will be funded, role and function of the office etc''.

The Coalition, if it won office, would announce a ''transitional period'' in which tougher assessment criteria would be applied to mining projects on agricultural land, including a ''pause'' on granting new mining titles. About 70 per cent of NSW is now under mineral and petroleum title or application.

The council advises against any pause, saying it should be ''made more transparent and the community will be given a say''.

The Coalition would also move to introduce aquifer interference regulation in a bid to protect agricultural water supplies.

A senior government source said it was ''extraordinary'' to allow pressure groups to actively rewrite election policies. ''I've never heard of this before,'' the source said.

Mr Gay said it was not unusual to ''consult widely'' on policies. ''Our final policy will show that we are not beholden to either miners or farmers,'' he said.

A spokesman for the minerals council chief executive, Nicole Williams, said miners had been working ''side-by-side'' with farmers on the policy. ''Both bodies have provided comments and feedback on innumerable versions of this draft policy,'' he said.

The farmers association president, Charles Armstrong, said he was confident that the final Coalition policy would reflect farmers' concerns.

"The NSW Farmers Association is still negotiating matters relating to mining policies with the NSW opposition,'' he said.

''We are confident our policies will be reflected in their policy document.''