Tony Blair appears at UK inquiry into Iraq War (VIDEO)

Former British Prime Minister Tony Blair has made his second appearance in a year at the Chilcot Inquiry into the origins and conduct of the Iraq war.

Blair was asked to return to fill in gaps from earlier testimony about his unpublicized discussions with former President George W. Bush as the conflict loomed, according to The New York Times.

The last time Blair appeared before the inquiry, in January 2010, he was questioned for six hours. He defended his decision then to lead Britain into a deeply unpopular war, saying he would do the same again to counter what he depicted as a threat from Saddam Hussein.

And on Friday, he again invoked the Sept. 11 attacks as the source of his subsequent policies towards Iraq, terrorism and unconventional weapons.

According to the Guardian, he told the inquiry that he had offered Bush Britain's support in tackling the terrorist threat. He supported the containment of the Iraq regime and then the presentation of an ultimatum to Saddam.

Blair told the inquiry that despite suggestions to the contrary, cabinet ministers had been kept fully informed and had taken part in full discussions about British plans, the Telegraph reported.

"We were on a course where the principles were absolutely clear: go down the U.N. route, get an ultimatum, if he fails to meet the ultimatum we will be with America on military action," he said, adding that the suggestion anyone in the Cabinet could be unaware of military preparation "defied common sense and logic."

Blair also faced questions over whether he pressured his then attorney general, Peter Goldsmith, to endorse the legality of the war.

He said he regarded the advice of his government's attorney general that the invasion of Iraq would be illegal as only "provisional" during the runup to the war, and that he was entitled to ignore the advice of Goldsmith.

Early during the hearing, Blair was challenged by panel member Martin Gilbert as to whether he regretted comparing the threat from Saddam Hussein's regime to Nazi Germany in the 1930s.

Blair conceded he should not have implied the circumstances were the same, but insisted he still believed the "calculus of risk" had altered in the wake of the 9/11 attacks in the United States in 2001.