Washington ? Former Treasury Secretary Paul O’Neill on Tuesday denied that classified documents were used in a controversial new book in which he paints an unflattering portrait of President Bush. He softened some of his criticism in the face of a strong counterattack by the administration.

The Inspector General’s Office at Treasury confirmed that it had begun an investigation into whether any laws or regulations had been violated when Treasury employees turned over 19,000 documents to O’Neill after he was fired by Bush in December 2002.

Meanwhile, the administration intensified its criticism of O’Neill’s assertions in the book, “The Price of Loyalty,” including his charge that Bush had begun planning to overthrow Saddam Hussein in the first days of his presidency.

Defense Secretary Donald Rumsfeld, echoing comments Bush made in Mexico, said that the administration was simply following the policies of “regime change” of the Clinton administration and Bush did not commit to a war with Iraq until shortly before the invasion began last March.

Rumsfeld also told reporters at the Pentagon that his experiences in the administration were “night and day” different from the detached president described by O’Neill. The Treasury secretary said Bush so seldom asked questions during Cabinet meetings that it reminded him of a “blind man in a room full of deaf people.”

Rumsfeld said he had called O’Neill, his friend since the 1960s, and cautioned him against participating in any kind of kiss-and-tell book about the two years he spent in the administration before Bush fired him in December 2002.

O’Neill said he was sorry about one thing. “I used some vivid language, that if I could take it back, I’d take it back because it’s become the controversial centerpiece. … It’s not my intention to be personally critical of the president or of anyone else,” he said.

Appearing on NBC’s “Today” program, O’Neill denied that any classified government documents had been used in the book, which he said was written to inform the public about a “broken political process” in which serious problems such as the looming crisis in Social Security and Medicare could not be debated responsibly in Washington’s political atmosphere.

O’Neill said the Treasury Department’s general counsel’s office, responding to his request for copies of all documents that had crossed his desk at Treasury that were not classified, had given him computer disks containing 19,000 separate documents, which he turned over to author Ron Suskind without reviewing.

He said if any classified material had mistakenly been turned over, it would have been the fault of Treasury employees because he had not taken any documents with him when he left.