WASHINGTON – Alan Greenspan, the former Federal Reserve chairman, said in an interview that the removal of Saddam Hussein had been “essential” to secure world oil supplies, a point he emphasized to the White House in private conversations before the 2003 invasion of Iraq.

Greenspan, who was the country’s top voice on monetary policy at the time Bush decided to go to war in Iraq, has refrained from extensive public comment on it until now, but he made the striking comment in a new memoir out yesterday that “the Iraq War is largely about oil.” In the interview, he clarified that sentence in his 531-page book, saying that while securing global oil supplies was “not the administration’s motive,” he had presented the White House with the case for why removing Hussein was important for the global economy.

“I was not saying that that’s the administration’s motive,” Greenspan said in an interview Saturday, “I’m just saying that if somebody asked me, ‘Are we fortunate in taking out Saddam?’ I would say it was essential.”

He said that in his discussions with President Bush and Vice President Dick Cheney, “I have never heard them basically say, ‘We’ve got to protect the oil supplies of the world,’ but that would have been my motive.” Greenspan said that he made his economic argument to White House officials and that one lower-level official, whom he declined to identify, told him, “Well, unfortunately, we can’t talk about oil.” Asked if he had made his point to Cheney specifically, Greenspan said yes, then added, “I talked to everybody about that.”

Greenspan said he had backed Hussein’s ouster, either through war or covert action. “I wasn’t arguing for war per se,” he said. But “to take [Hussein] out, in my judgment, it was something important for the West to do and essential, but I never saw Plan B” – an alternative to war.

Greenspan’s reference in “The Age of Turbulence: Adventures in a New World” to what he calls the “politically inconvenient” fact that the war was “largely about oil” was first reported by The Washington Post on Saturday and has proved controversial.

Defense Secretary Robert Gates took issue with Greenspan on ABC’s “This Week” Sunday. “I wasn’t here for the decision-making process that initiated it, that started the war,” Gates said. But, he added, “I know the same allegation was made about the Gulf War in 1991, and I just don’t believe it’s true.”

Critics of the administration have often argued that while Bush cited Hussein’s pursuit of weapons of mass destruction and despotic rule as reasons for the invasion, he was also motivated by a desire to gain access to Iraq’s vast oil reserves. Publicly, little evidence has emerged to support that view, though a top-secret National Security Presidential Directive, titled “Iraq: Goals, Objectives and Strategy” and signed by Bush in August 2002 – seven months before the invasion – listed as one of many objectives “to minimize disruption in international oil markets.”