US President George W. Bush said in an interview set for broadcast Monday that he came to office "unprepared for war" and that his "biggest regret" was the US "intelligence failure" on Iraq.

In a wide-ranging exchange with ABC television''s "World News Tonight," Bush also said he was "sorry" that the global economic meltdown was taking place and predicted that he would leave office January 20th with his "head held high."

The US president has been mired in record-low approval ratings after the botched government response to killer Hurricane Katrina (2005) and amid wars in Iraq and Afghanistan, as well as the world financial crisis.

"The biggest regret of all the presidency has to have been the intelligence failure in Iraq," Bush said 50 days before president-elect Barack Obama''s inauguration. "I wish the intelligence had been different, I guess."

But Bush refused to say whether he would have ordered the March 2003 invasion if he had known that late dictator Saddam Hussein did not have weapons of mass destruction, calling it "an interesting question."

"That is a do-over that I can''t do. It''s hard for me to speculate," said Bush, who declared as recently as last week that Saddam''s ouster was "the right decision then -- and it is the right decision today."

More than 4,200 US troops have died in Iraq since Bush launched the war after a months-long public campaign centered on the charge -- later proved false -- that Saddam possessed vast stockpiles of weapons of mass destruction.

"A lot of people put their reputations on the line and said the weapons of mass destruction is a reason to remove Saddam Hussein. It wasn''t just people in my administration," Bush told ABC.