Former White House aide Lewis (Scooter) Libby was sentenced to 2½ years in prison Tuesday for lying and obstructing the CIA leak investigation.

Libby, the former chief of staff to Vice-President Dick Cheney, stood calmly before a packed courtroom as a federal judge said the evidence overwhelmingly proved his guilt.

"People who occupy these types of positions, where they have the welfare and security of nation in their hands, have a special obligation to not do anything that might create a problem," U.S. District Judge Reggie B. Walton said.

The judge also ordered Libby to pay a $250,000 US fine and imposed a two-year probation.

U.S. President George W. Bush feels "terrible" for Libby's family, a White House spokesperson said Tuesday. Bush was told about the sentence while in Europe for the Group of Eight summit.

"The president has not intervened so far in this or any other criminal matter, so he's going to decline to do so now as well," said White House deputy press secretary Dana Perino.

Libby is the highest-ranking White House official convicted in a government scandal since the Iran-Contra affair two decades ago. He was convicted in March of lying about what he told reporters regarding CIA operative Valerie Plame, whose identity was leaked in 2003 after her husband criticized the Bush administration's Iraq war policies.

Libby was not charged with the leak itself — in fact, no one has been charged with leaking Plame's name.

Libby has not discussed the case since his 2005 indictment on perjury and obstruction of justice charges. Throughout his month-long trial, and following his conviction in March, he always let his lawyers do the talking.

On Tuesday, however, before Walton handed down the sentence, he asked Libby whether he had anything to say.

"It is respectfully my hope that the court will consider, along with the jury verdict, my whole life," Libby said in brief remarks to the judge.

The defence team had argued that Libby should be given a lenient sentence because of his lengthy career in public service. Special prosecutor Patrick Fitzgerald had asked that Libby serve up to three years in prison, in part because he has shown no remorse.

Legal experts say his prison sentence could very well be suspended as Libby's lawyers appeal. Walton has not yet said whether Libby could remain free pending appeal.

In March, White House press secretary Tony Snow brushed off questions about whether Bush would entertain a pardon for Libby, saying the case remains under legal review.

In 1992, as Bush's father, President George H.W. Bush, was preparing to leave office, he granted pardons for former officials in Ronald Reagan's administration. They had been caught up in the scandal that grew out of arms sales to Iran and the diversion of proceeds to the Nicaraguan rebels.

With files from the Associated Press