NSW irrigators reacted furiously to Mr Abbott's referendum announcement in January.

In late February they received a letter from Mr Truss pointing to two relevant National Party policies.

''You will note that neither policy advocates a referendum or any new transfer of powers from the states to the Commonwealth,'' Mr Truss wrote in the February 24 reply to the NSW Irrigators' Council.

The council chief executive, Andrew Gregson, said: ''They are telling us it is not their policy and they don't go along with it.

''They are telling us it's unlikely to happen. We hope it doesn't because we'd prefer to see how the current government's policy works. Abbott's plan would replace a system which has the capacity to work with one that won't.''

The National Party member for Riverina, Kay Hull, who represents hundreds of NSW irrigators, told Mr Abbott during Tuesday's party-room meeting that she did not support the idea which could mean that a federal minister from South Australia controlled water use for her constituents.

Her opposition prompted a rebuke from the South Australian Liberal MP and member for Mayo, Jamie Briggs, whose seat includes the lower reaches of the Murray and the associated lakes.

Sources said Mr Briggs, in the party room, defended the prospect of a referendum. He said Mr Abbott's remarks were ''cutting through'' in SA where there is anger at the upstream states hiving off water for irrigation.

But Mr Gregson said that NSW irrigators had been even more angered when Mr Abbott visited South Australia in February and pointed to ''overallocation upstream'' as part of the problem.

He said Mr Abbott should ''have a grasp of the entire river system before he starts shooting from the lip''.

The opposition water spokesman, Ian Macfarlane, said the referendum was a ''last resort option'' and he thought the concerns of the NSW and Victorian irrigators, and the National Party MPs, could be resolved by making it clear the referendum would not be used to alter existing water use agreements prior to their expiry dates, and that property rights would be respected.

Mr Abbott said that if the states did not voluntarily refer their powers to manage the basin by 2012, a Coalition government would hold a referendum for a federal takeover at the next election in 2013.