Barack Obama defends Chelsea Manning's release

Outgoing US President Barack Obama has defending freeing Chelsea Manning, convicted of leaking thousands of confidential documents, saying justice has been served.

Convicted under her former name Bradley, Manning will be released from an all-male military prison in May this year, rather than in 2045 when her 35-year sentence is up. Manning has served seven years of her sentence.

She was one of 209 other prisoners who had their sentences shortened as one of Mr Obama's final acts as President.

Manning's release has also been welcomed by the United Nations, which says it is time to recognise the work of whistleblowers.

In his final news conference before President-elect Donald Trump's inauguration this weekend, Mr Obama explained his decision.

"Chelsea Manning has served a tough prison sentence, so the notion that the average person who was thinking about disclosing vital classified information would think that it goes unpunished, I don't think would get that impression from the sentence Chelsea Manning has served.

"I feel very comfortable justice has been served."

He believed Manning's sentence was "disproportionate" in comparison to what other leakers had received.

"I felt in light of all the circumstances that commuting her sentence was entirely appropriate."

UN independent expert on the promotion of democratic and equitable international order, Alfred de Zayas, says while Manning's release is a cause for celebration there are still many whistleblowers in prison.

"It is time to recognise the contribution of whistleblowers to democracy and the rule of law and to stop persecuting them."

He called on the world's governments to end the "multiple campaigns of defamation, mobbing and even prosecution" of the likes of WikiLeaks founder Julian Assange and former NSA contractor Edward Snowden who "have acted in good faith".

"Whistleblowers who are serving prison sentence in many countries should be pardoned.

"Whistleblowers are human rights defenders whose contribution to democracy and the rule of law cannot be overestimated. They serve democracy and human rights by revealing information that all persons are entitled to receive."

Mr Obama says while there are some who believe protections for whistleblowers aren't strong enough, it is a different consideration when it comes to national security.

"I think all of us who are working in big institutions may find ourselves at times at odds with policies, but when it comes to national security you're dealing with the safety and security and the ability of our military or intelligence teams or embassies to function effectively and that needs to be kept in mind."