US whistleblower Chelsea Manning has been jailed for contempt of court after refusing to give evidence to a grand jury investigation into WikiLeaks.

Sending her to a federal prison on Friday, US District Judge Claude Hilton said she will remain behind bars until she testifies, or until the grand jury finishes its inquiry.

The former US Army intelligence analyst told the judge she will accept whatever you bring upon me.

Manning, 31, has said she objects to the secrecy of the grand jury process, and that she already revealed everything she knows at her court martial.

Her lawyers had asked that she be sent to home confinement instead of jail, because of medical complications she faces.

The judge said US Marshals can handle her treatment needs.

Manning was convicted of espionage and other offences by court-martial in 2013.

She leaked some 700,000 documents, videos, diplomatic cables and battlefield accounts to WikiLeaks while she was an intelligence analyst in Iraq in 2010.

Sentenced to 35 years in jail, she was released in 2017 after former US president Barack Obama commuted her sentence.

Previously known as Private Bradley Manning, the former soldier now chooses to identify as a woman and underwent gender transition while in jail.

Among the documents she released were millions of diplomatic cables and a 2007 video of a US helicopter in Baghdad firing on a group of civilians that killed two Reuters photographers and wounded two children.

On Wednesday, Manning appeared before the same grand jury, in the US District Court for the Eastern District of Virginia, but refused to answer any questions.

The day before, Manning told The Associated Press that she didn’t know what case she was being called to testify about and said: Grand juries are terrible, to say the least.

Manning’s support committee, Chelsea Resists!, called the grand jury system dangerous and undemocratic.

Grand juries operate in secret, allowing the government to retaliate against activists and dissidents behind closed doors, said a statement from the committee released by Manning’s lawyers.

(c) Sky News 2019: Chelsea Manning: US whistleblower jailed for refusing to testify at WikiLeaks investigation