The open letter on Sunday echoed similar statements issued earlier in the year by retired US and British officials, making Australia the latest of the pro-war allies to face criticism from its own former diplomats.
The statement said the electorate had been misled over the reasons for joining the US-led invasion of Iraq, and democracy could not work properly if people could not trust their elected representatives.
"We are concerned that Australia was committed to join the invasion of Iraq on the basis of false assumptions and deception of the Australian people," the statement said.
"Saddam's dictatorial regime has ended but removing him was not the reason given to the Australian people for going to war.
Howard denies misleading the
public over Iraq
"The prime minister said in March 2003 that our policy was the disarmament of Iraq not the removal of Saddam Hussein."
It said Australia's involvement had raised the country's profile as a "terrorist target".
The statement was signed by former defence force chiefs Alan Beaumont and Peter Gration, former defence department secretary Paul Barratt, former prime minister's department secretaries Alan Renouf and Richard Woolcott as well as former ambassadors, including Rawdon Dalrymple, Stephen Fitzgerald and Ross Garnaut.
Australia has been one of the strongest supporters of the Iraq campaign, committing about 2000 troops to last year's invasion and maintaining about 850 troops in and around the country.
"Australian leaders must produce more carefully balanced policies and present them in more sophisticated ways"
and defence chiefs
Howard has repeatedly denied misleading the public about the invasion, saying intelligence at the time indicated Iraq had weapons of mass destruction.
The signatories said they did not wish to endanger Australia's alliance with the US, but asserted that it should be a genuine partnership and not just a rubber stamp for policies decided in Washington.
"Australian leaders must produce more carefully balanced policies and present them in more sophisticated ways," they wrote.
In April, a group of former diplomats sent a letter to British Prime Minister Tony Blair savaging "doomed policies" in Iraq and the Middle East.
The letter was echoed by retired US diplomatic and military officials in two separate letters in May and June accusing President George Bush of undermining US credibility in the Arab world and calling for him to be voted out over Iraq.