US president George W. Bush said on Tuesday he was unaware if, during his eight-year tenure, Al-Qaida chief Osama bin Laden was ever close to being captured.

In a farewell interview of the presidential couple with CNN's Larry King, Bush said he was "absolutely" certain bin Laden will be caught sooner or later, "because we have a lot of people looking for him."

Asked if the September 11 mastermind ever came close to being captured since US forces went into Afghanistan looking for him in 2002, Bush said: "I don't know. I can't answer that."