Chelsea Manning, the US soldier serving a 35-year prison sentence for passing a trove of secret documents to WikiLeaks, started posting on Twitter on Friday, with help from supporters.

Within minutes of her first tweets, Manning had recruited more than 5,000 followers under the handle @xychelsea.

In her initial tweets, Manning acknowledged she had no Internet access behind bars and that she was dictating comments to her supporters by telephone.

"Tweeting from prison reqs a lot of effort and using a voice phone to dictate #90s problems," she wrote.

But Manning, 27, said she still had hopes to promote a genuine online dialogue. "It will be hard, but I don't want this Twitter feed to be a one-way street/conversation."

Manning already writes occasional commentaries for The Guardian newspaper's American edition, offering her take on US foreign policy.

The former army intelligence analyst was convicted in August 2013 of espionage and other offenses after admitting to handing over more than 700,000 classified documents, including military intelligence reports and State Department cables, to the anti-secrecy website WikiLeaks.

US officials describe Manning's document dump as the biggest leak of classified files in American history.

On Manning's request, judges have ordered the military to address Manning in gender-neutral or feminine terms in court documents as she completes her transition to life as a woman.

After months of legal wrangling, the US Army recently approved hormone therapy for Manning's gender "reassignment," an unprecedented step for the military.

Manning, who was formerly a male enlistee known as Bradley Manning, is serving out her sentence at Fort Leavenworth prison in Kansas.