WASHINGTON: President Barack Obama said on Wednesday that former military intelligence analyst Chelsea Manning had served a tough prison term and his decision to commute her 35-year sentence to about seven years served would not signal leniency toward leakers of US government secrets.

Obama told his final news conference as president that he felt it made sense to commute Manning's sentence because she went to trial, took responsibility for her crime and her sentence was disproportionate to those received by other leakers.

"Chelsea Manning has served a tough prison sentence," Obama said of his decision to reduce her sentence, which was announced Tuesday in a batch of 209 commutations and 64 pardons granted. "I feel very comfortable that justice has been served."

Manning gave classified information of more than 700,000 documents, videos, diplomatic cables and battlefield accounts to anti-secrecy group WikiLeaks in 2010, the biggest such breach in US history.

Congressional Republicans criticized the commutation as a dangerous precedent for leakers. Sean Spicer, the press secretary for President-elect Donald Trump, told reporters Wednesday it sent a "very troubling message."

Obama said the commutation was done without regard to WikiLeaks founder Julian Assange, who said on Twitter last Thursday that if Manning was freed, he would accept extradition to the United States, where there is an open criminal investigation into the activities of WikiLeaks.

"I don’t pay a lot of attention to Mr Assange’s tweets," Obama said, adding that he did not see a contradiction with his administration's approach to Assange and Manning and referring more questions on WikiLeaks to the Justice Department.

“What I can say broadly in this new cyber age, we’re going to have to continually work to find the right balance of accountability and openness and transparency that is the hallmark of our democracy, but also recognize that there are adversaries and bad actors out there who want to use that same openness in ways that hurt us," Obama said.

Barry Pollack, a US-based lawyer for Assange, said in an email Wednesday that Obama's commutation of Manning fell "well short" of what Assange sought because he had called for her "to receive clemency and be released immediately."

A US official said the Justice Department was investigating "civilian" individuals associated with the leaking of government secrets via WikiLeaks.

"The Department of Justice is conducting an investigation and it remains ongoing. I am not able to provide any further information," said Joshua Stueve, a spokesman for the US Attorney's office in Alexandria, Virginia.

WikiLeaks returned to prominence during the 2016 US presidential election, publishing hacked emails stolen from the Democratic National Committee and the accounts of senior Democrats.

US intelligence agencies have concluded that Russian intelligence agencies were responsible for the hacks and that they were carried out as part of a campaign by Moscow to help Republican Donald Trump win and discredit Democrat Hillary Clinton.

Obama said the intelligence agencies were not conclusive in their assessment of the hacks "whether WikiLeaks was witting or not in being a conduit" for Russia's efforts to use cyber attacks to influence the election. Assange has said the Russian government was not the source of the emails.

Manning, formerly known as US Army Private First Class Bradley Manning, was born male but revealed after being convicted of espionage that she identifies as a woman. The White House said on Tuesday that her sentence would end on May 17 this year.

Manning twice tried to kill herself last year and has struggled to cope as a transgender woman in the Fort Leavenworth, Kansas, men's military prison. Her case became a rallying cause for civil liberties advocates who saw the punishment as too severe and an attempt to chill whistleblowers from speaking up about government misdeeds.