LIBERAL leader Tony Abbott has come under fire from irrigators and the Nationals over water policy.

The controversy follows Mr Abbott's claim that problems in the lower end of the Murray-Darling Basin were caused by over-allocation upstream.

Mr Abbott also said if the states refused to hand their Basin powers to the Commonwealth, he would seek a referendum in a bid to force them.

NSW Irrigators' Council chief Andrew Gregson, Victorian Farmers Federation water council chair Richard Anderson and Nationals MP John Forrest all said Mr Abbott failed to understand the issue.

Mr Gregson accused Mr Abbott of abandoning rural seats to pander to marginal suburban seats in Adelaide while Mr Forrest said "people need to be better briefed when they comment on the MD basin".

"We have nothing but horrendous problems here because people who sit in ivory towers know nothing about water," Mr Forrest told The Weekly Times.

Mr Gregson called on the Nationals to "stand up for rural and regional NSW against Abbott".

Mr Anderson said the term "over-allocation" was incorrect and that states should not hand any further power to the Commonwealth.

"He (Mr Abbott) can make all the noise he likes, but we won't change our position," Mr Anderson said.

He said the Nationals were "basically country-based" and "you'd expect them to look after their constituents".

A spokesman for Nationals leader Warren Truss said the Nationals supported referral of state powers to the Commonwealth.

"It's difficult, we understand irrigators' concerns," the spokesman said.

"(But) we've got $6 billion sitting there ready to be used for water infrastructure . . . we support the use of that money to build the infrastructure."

Mr Abbott did not respond directly to the criticism from irrigators or Mr Forrest.

However, he said the Government was "solely focussed on buy-backs in the absence of a long-term plan".

The Coalition would invest in water infrastructure to "provide farmers with the tools to do more", he said.