WASHINGTON  Scott McClellan, President Bush’s former press secretary, told the House Judiciary Committee on Friday that he had been unfairly vilified by Bush supporters for his recent book criticizing former White House colleagues over the Iraq war and their involvement in leaking the identity of an intelligence officer.

Mr. McClellan, however, offered little new information in his testimony on those issues beyond what he wrote in the book, “What Happened: Inside the Bush White House and Washington’s Culture of Deception” (PublicAffairs), which was published in May and last week topped the nonfiction best-seller list in The New York Times.

In the book, Mr. McClellan says senior White House officials misled the nation about the reasons for invading Iraq and maneuvered him into lying to the public about their roles in the leak case.

The book, with Mr. McClellan’s lacerating criticism of his former colleagues, has generated a rich discussion about the obligations of political loyalty, and his appearance Friday on Capitol Hill provided another stage for that debate. The man who once regularly and seemingly by rote defended Mr. Bush in the White House press room was attacked by the committee’s ranking Republican, Representative Lamar Smith of Texas, who grilled Mr. McClellan as ferociously as any reporter had in his three years as press secretary.