Coalition deal not shown to Cosgrove

Governor-General Peter Cosgrove did not seek or receive details of the new Liberal-National coalition agreement signed in the wake of Malcolm Turnbull ousting Tony Abbott.

Sir Peter received a brief letter from National leader Warren Truss on September 15 last year assuring him Mr Turnbull had the Nationals' support in forming government.

But he did not receive any written advice on the details of the coalition agreement, the governor-general's secretary Mark Fraser told a Senate committee on Monday.

"They are not matters with which the governor-general would ordinarily involve himself," Mr Fraser said.

Sir Peter met with Mr Turnbull but no details of the private conversation were available.

Asked whether a fresh letter would be needed if the National leadership changed in the future, Mr Fraser said: "It would be up to the governor-general whether he would like that assurance."

The Nationals received a number of concessions from Mr Turnbull in the new agreement, on issues ranging from water policy to competition policy.