Bradley Manning has been sentenced to 35 years in jail for giving WikiLeaks files that formed the biggest breach of official secrets in American history.

The 25-year-old could apply for parole and be freed within a decade, and his lawyer has issued a plea to president Barack Obama to pardon the soldier.

Manning had faced up to 90 years in prison for providing more than 700,000 documents, battle videos and diplomatic cables to the anti-secrecy website.

He appeared ashen-faced moments before he heard his fate in a courtroom at Fort Meade military base in Maryland, close to the US capital.

Key points: Bradley Manning sentenced to 35 years in jail over leaks

Bradley Manning sentenced to 35 years in jail over leaks Under military law he is eligible for parole on completion of one-third of the sentence

Under military law he is eligible for parole on completion of one-third of the sentence That means with time already served, he could apply be freed in nine years

That means with time already served, he could apply be freed in nine years Manning's lawyer has asked Barack Obama to pardon the soldier

Manning's lawyer has asked Barack Obama to pardon the soldier WikiLeaks has hailed the decision as a "significant strategic victory"

Military judge Colonel Denise Lind delivered her verdict in a less than two-minute statement, saying Manning would be demoted from private first class to private E1 status, and later dishonourably discharged.

Under military law Manning is eligible for parole on completion of one-third of his sentence, which is slightly more than half the 60 year term that prosecutors had pushed for.

His jail time will be shortened by a total of 1,293 days on account of the more than three years he has already served, which means he could be freed in nine years.

A video-link to the courtroom cut out as soon as Colonel Lind stopped speaking, but several Manning supporters were seen in tears outside immediately following the sentencing announcement.

Manning's lawyer David Coombs said he would ask Mr Obama to pardon him "or at the very least commute his sentence".

An emotional Mr Coombs read a letter Manning addressed to Obama: "If you deny my request for a pardon I will serve my time knowing that sometimes you have to pay a heavy price to live in a free society."

The White House has sidestepped the appeal.

"If there is an application that's filed by Mr Manning or his attorneys, that application will be considered ... like any other application," spokesman Josh Earnest said.

Assange hails 'tactical victory'

Sorry, this video has expired Assange calls Manning sentence 'a tactical victory' ( Michael Rowland )

Civil liberties groups condemned the sentence, but WikiLeaks founder Julian Assange hailed it as a "tactical victory".

Mr Assange remains holed up in Ecuador's embassy in London, where he is trying to avoid extradition to Sweden on sexual assault allegations.

"This is a really important tactical victory for his defence team, his campaign team and his support community," he told ABC News Breakfast.

"But that said, Bradley Manning shouldn't be doing any time in prison at all."

Mr Assange accused the US of trying to set an example by its treatment of Manning.

"It was trying to smash a nut with a sledge hammer. It abused the court process, it abused the detention process," he said.

"It was designed to act as a general deterrent from anyone else revealing information about the US government.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 3 m Manning gets 35 years in WikiLeaks trial ( Jane Cowan ) Download 1.4 MB

"That general deterrent, it has failed. The attack against Bradley Manning has failed."

Mr Assange had earlier issued a statement saying the government had demonstrated "that there is no place in its system for people of conscience and principle".

"As a result, there will be a thousand more Bradley Mannings," he said.

Manning had faced months-long trial

Manning was convicted of espionage and other crimes last month, having earlier admitted being the source of the leaks.

Publication of the documents caused deep embarrassment to the United States and rankled American allies, prompting warnings from US officials that troops and intelligence sources had been jeopardised.

Who is Bradley Manning? Born in Crescent, Oklahoma, reportedly created first website at age 10

Born in Crescent, Oklahoma, reportedly created first website at age 10 Was into computer hacking before joining the US army

Was into computer hacking before joining the US army Bullied over his homosexuality and gender identity issues

Bullied over his homosexuality and gender identity issues US army private, now aged 26, was posted to Iraq in 2009 as an intelligence analyst

US army private, now aged 26, was posted to Iraq in 2009 as an intelligence analyst Arrested in 2010 and accused of the biggest leak of government secrets in US history

The 35-year jail term will be considered especially important as another leaker - former intelligence contractor Edward Snowden, currently in Russia - is wanted in the United States on espionage charges, having disclosed details of the National Security Agency's secret electronic monitoring operations.

Army lawyers had pressed for a much longer sentence, arguing that significantly more jail time would send a message to people contemplating the theft of classified information.

Lead defence attorney David Coombs, however, appealed for leniency for his client.

He said Manning had expressed remorse, cooperated with the court and deserved a chance to have a family and one day walk free.

Manning was working as a low-level intelligence analyst in Baghdad when he handed over the documents, catapulting WikiLeaks and Mr Assange into the international spotlight.

He was arrested in Iraq in 2010 and has since been in military custody.

The years-long legal process that finally culminated in his conviction and sentencing offered an astonishing view inside the young soldier's mind before, during and after he was deployed in Iraq.

The most notorious material that he brought to light was a video file, dubbed "Collateral Murder" by WikiLeaks, showing graphic cockpit footage of two US Apache attack helicopters opening fire and killing 12 people in Baghdad in 2007.

Among the fatalities were two Reuters news staff.

Manning, a hero to supporters who regard him as a whistleblower who lifted the lid on America's foreign policy, openly condemned the remarks of the pilots, who had branded the victims "dead bastards".

Shock at length of sentence

Though found guilty of 20 of the 22 offences levelled against him, Manning was cleared of the most serious charge - aiding the enemy, chiefly Al Qaeda.

More than 100,000 people have signed a petition calling for Manning's nomination for a Nobel Peace Prize.

Former military lawyer Dan Mori, who represented Guantanamo detainee David Hicks, says he is shocked by the length of Manning's "excessive" sentence.

"A JAG officer got convicted of espionage for leaking names from Guantanamo. He only got six months," he told ABC News Breakfast.

Sorry, this video has expired Former US military lawyer Dan Mori calls Manning sentence 'excessive' ( Michael Rowland and Virginia Trioli )

"But that gives you a comparison. The one thing that's hard to assess is we don't know the secret evidence that the judge saw and how that factored into her decision and whether it drove up the sentence."

The American Civil Liberties Union says the sentence was sad for Manning but also sad "for all Americans who depend on brave whistleblowers and a free press for a fully informed public debate".

"When a soldier who shared information with the press and public is punished far more harshly than others who tortured prisoners and killed civilians, something is seriously wrong with our justice system," they added in a statement.

Expert witnesses testified during the sentencing phase of Manning's trial that the soldier was confused about his gender and sexuality and under enormous psychological stress at the time he committed the leaks.

Manning also apologised. He told Colonel Lind during a hearing last week: "I'm sorry that my actions have hurt people and have hurt the United States."

AFP