Lewis "Scooter" Libby, a former top aide to Dick Cheney, the US vice president, has been found guilty of four counts of lying, perjury and obstructing justice during an investigation tied to the Iraq war.

Democrats say other officials should also have been prosecuted while Cheney said he was "very disappointed" by the verdict.

Libby could be jailed for 25 years and fined millions of dollars.

Investigators had sought to determine who leaked the identity of Valerie Plame, a CIA analyst, to the press in 2003 after her husband accused the Bush administration of manipulating intelligence to build its case for the Iraq war.

Push for war

Libby spent four years as chief of staff to Cheney and, as a leading member of the neoconservatives, he and the vice president were among those senior politicians who drove the push for a war in Iraq.

The speaker of the House of Representatives, Nancy Pelosi, said: "The testimony unmistakably revealed - at the highest levels of the Bush administration - a callous disregard in handling sensitive national security information and a disposition to smear critics of the war in Iraq."

The jury of seven women and four men determined he obstructed the probe and lied to investigators.

Libby, who left the courthouse grim-faced after the verdict, has been allowed to remain free while awaiting sentencing.

His lawyers had said he could not accurately recall conversations about Plame when he was interviewed months later by the FBI and a grand jury.

Libby was found not guilty of an additional count of lying to the FBI.

'Fall guy'

Nobody has been charged with intentionally identifying Plame, the wife of former ambassador Joseph Wilson.

Democrats said the "real tragedy" was that other senior Bush administration officials who were involved remained unpunished and in their jobs.

Chuck Schumer, a Democratic senator and chairman of the senate judiciary subcommittee on courts, said after Tuesday's verdict: "In a very real sense, Scooter Libby ended up being the fall guy.

"The evidence in the trial made clear that there were many others involved in manipulating intelligence and leaking classified information to intimidate those who were telling the truth."

Ted Kennedy, another senator, said the verdict "confirms the lengths to which the White House - particularly the office of the vice-president - was willing to go to conceal their effort to vilify anyone who spoke the truth about the flaws in their justification for war".

Story invented

Prosecutors said Libby discussed Plame's name with reporters and, fearing prosecution, made up a story to make those discussions seem innocuous.

Libby's defence team said he learnt about Plame from Cheney, forgot about it, then learnt it again a month later from Tim Russert, a journalist for NBC.

Anything he told reporters about Plame, Libby said, was just "chatter and rumours," not official government information.

Patrick Fitzgerald, the special prosecutor, said that was a lie but defence attorneys said it would be unfair to convict Libby in a case where so many witnesses changed their stories or had memory problems.

Reggie Walton, a US district judge, said: "I can't say I've seen a better group of jurors who conscientiously listened to the evidence and went about the business of deciding the case."

Walton ordered a pre-sentencing report be completed by May 15. Judges use such reports to help determine sentences.

Cheney 'saddened'

Libby's defence attorney, Theodore Wells, said he would ask the court for a new trial by April 13. Such requests are common after criminal convictions.

Cheney said he was saddened for his former right-hand man and his family.

"As I have said before, Scooter has served our nation tirelessly and with great distinction through many years of public service," he said.

The White House said the president "respected the jury's verdict, that he was saddened for Scooter Libby and his family".

Dana Perino, a spokeswoman for George Bush, refused to discuss whether the president would consider using his constitutional power to pardon Libby, who also served as "assistant to the president" before he resigned when he was indicted in October 2005.

PHOTO CAPTION

Former White House aide I. Lewis 'Scooter' Libby, leaves federal court in Washington, Tuesday, March 6, 2007. (AP)