WASHINGTON, April 20: US Secretary of State Colin Powell denied as "silly" on Monday that he learned of President George Bush's decision to invade Iraq after Saudi Arabia was informed, as journalist Bob Woodward has said.

Despite questions raised by a new Woodward book, "Plan of Attack", that Mr Powell had misgivings over the invasion, the retired general also said he knew he would support an invasion if he failed to find a diplomatic solution at the United Nations.

"I knew that it might happen, and I knew that when he (Bush) took that second road, I'd be with him for the whole way. I don't quit on long patrols," Mr Powell said on the Sean Hannity radio show.

"I believe it was the right decision at the time (to go to war), and I believe it is the right decision now," he added. The book has fueled election-year claims of rifts in the administration and that Mr Bush was eager to invade Iraq despite warnings over an occupation that has turned out to be far more deadly for U.S. troops than the war.

Mr Powell, who has been perceived as the most reluctant among Mr Bush's key advisers to occupy Iraq, sought to defend his positions on the war after Woodward said he tussled with other top officials and was out of the loop on the final decision. "When I told the president, 'This is going to be difficult, especially in the aftermath, and we are responsible for Iraq,' then I was doing my job," Mr Powell said.

Mr Bush told national security adviser Condoleezza Rice, Vice President Dick Cheney and Defense Secretary Donald Rumsfeld first about his decision to go to war in January 2003, according to Woodward. A detailed plan was also shown to Saudi Ambassador to the United States Prince Bandar bin Sultan before Mr Bush told Mr Powell of his final decision, Woodward said. -Reuters