Niall Blair, the state's water minister, is upset that some in his own party sought to undermine him as he worked to secure a drought package for struggling farmers.

He took to task colleagues Adam Marshall and Michael Johnsen after the pair issued media statements calling for more government drought action even though a $500,000 relief package was about to be announced.

It is understood the MPs were authorised to make the statements by Nationals leader John Barilaro who's also the deputy premier.

"They know I was disappointed, particularly because we were working so hard to deliver that extra assistance to farmers," Mr Blair told AAP on Tuesday.

"All they had to do was pick up the phone and have a chat. I could have updated them as to where we were up to."

Both Mr Johnsen and Mr Marshall issued press releases on July 25 calling for more government drought assistance.

The government announced its package five days later taking the state's overall drought assistance measures to more than $1 billion.

Mr Blair said he had been working on the deal for "many months".

As infighting within the NSW Nationals builds, 99 per cent of the state has been declared drought affected, with farmers facing one of the driest winters on record.

Australian Associated Press