A Liberal senator has criticised the former Howard government's record on foreign policy in an academic paper.

A Liberal senator has criticised the former Howard government's record on foreign policy in an academic paper.

Senator Russell Trood criticised the Iraq war and other policies in a paper on Australian foreign affairs written for the Lowy Institute.

The 200-page paper was launched by Opposition Leader Brendan Nelson at Parliament House in Canberra on Tuesday night.

"In response to climate change, for example, our response to this issue was, to say the least, uneven," Mr Trood said at a press conference reported by ABC radio.

"The Pacific Solution overshadowed the considerable strengths of a well conceived and responsible immigration policy.

"Iraq was an ill conceived enterprise from the very beginning.

"We were also unwise not to fund the Department of Foreign Affairs and Trade (DFAT) adequately."

Senator Trood, who holds a PhD in international relations, has long been a critic of the war in Iraq.

The ABC reported that former foreign affairs minister Alexander Downer called Senator Trood Tuesday night to berate him over the commentary.

The senator told ABC radio his paper was about the nation's future direction, not the opinion of the former foreign affairs minister.

"This is not about any conversations I might have had with Alexander Downer," he said. "The paper is about the future; it is about the challenges in the international environment that we face in Australia, and the purpose of this exercise is to look at those challenges and decide how Australia can best respond."

In launching the paper, Dr Nelson said he did not agree with everything Senator Trood said.

"No, I don't, but it's a free country, it's a Liberal party and everybody is entitled to a point of view," the opposition leader told ABC radio.

Liberal frontbencher George Brandis said Senator Trood had the right to speak out about foreign policy.

"It is perfectly proper and indeed healthy for a party that has recently gone into opposition ... to appreciate the legacy and look critically at our past," Senator Brandis told ABC radio.

He said it was not the role of Mr Downer, who has signalled he will be leaving parliament, to attempt to stifle the commentary.

"People who served in the previous government, who have indicated their intention to leave the parliament, one might think perhaps they've had their time and it's not their role now to try to constrain or stifle new voices who want to reassess the party's future."

Meanwhile, former Howard government minister Ian Macfarlane says Liberal MPs are able to freely debate issues within the party because they are not restricted by unions or rules.

Mr MacFarlane said neither Mr Trood or Mr Downer man had overstepped the mark.

"The Liberal Party is a broad church and we always debate issues very vigorously and if individuals disagree they usually express that disagreement," Mr Macfarlane told reporters outside Parliament House in Canberra.

"We're not bound by unions or rules in that regard and we're not restricted in the debate that we have."

Source: Australian Associated Press