Prime Minister John Howard insisted oil had nothing to do with Australia's involvement in the Iraq war, contradicting his defense minister who said Thursday that protecting Iraq's oil supplies is one of his country's motivations for keeping troops there.

Defense Minister Brendan Nelson's inclusion of global energy security as a reason for keeping troops in Iraq seemed likely to add weight to war protesters' arguments that the 2003 U.S.-led invasion was more an oil grab than a bid to uncover Saddam Hussein's weapons of mass destruction, which proved to be nonexistent.

Howard denied any connection between Iraq's oil, the invasion and the ongoing occupation.

"We are not there because of oil and we didn't go there because of oil," Howard told Sydney Radio 2GB. "A lot of oil comes from the Middle East — we all know that — but the reason we remain there is that we want to give the people of Iraq a possibility of embracing democracy."

Nelson, who became defense minister in January last year, told Australian Broadcasting Corp. radio that the foremost reason behind Australia's decision to remain in Iraq was "to make sure a humanitarian crisis does not develop between Sunnis and Shiites and driven by Al Qaeda if we were to leave prematurely."

He said other reasons — which the government has previously stated — included supporting a key ally, the United States, and ensuring stability in the Middle East and defeating terrorism.

"For these reasons in particular ... one of which is energy security, it is extremely important that Australia take the view that it's in ... our security interests to make sure that we leave the Middle East, and leave Iraq in particular, in a position of sustainable security," Nelson told ABC.

He went on to say that the Middle East as a whole is an important supplier of oil, and that Australians "need to think what would happen if there were a premature withdrawal from Iraq."

Prime Minister John Howard, a close ally in President Bush's war on terror, sent 2,000 troops to support U.S. and British forces in the Iraq invasion.

Australia maintains 1,000 troops in Iraq supported by 600 air force and navy personnel in the region.

The opposition Labor Party, which opposed the war, has pledged to remove most of Australia's troops from Iraq if it wins elections due late this year.

Labor defense spokesman Robert McClelland accused the government of shifting from its denial that oil was a motivation for the war.

"It's taken them four years to acknowledge that fact," McClelland said.

In a speech on Australia's current and future security threats, Howard highlighted diminishing oil as a danger to global peace. He later told 2GB he had not mentioned Iraq.

Globalization could "spur a resurgence of protectionism and increasing rivalry over globally traded resources, particularly oil," he said.