Representatives of Julian Assange welcomed the commutation of whistleblower Chelsea Manning's sentence, but have not confirmed whether the WikiLeaks founder will make good on his promise of allowing himself to be tried in the United States.

US. President Barack Obama on Tuesday commuted Manning's sentence from 35 years in prison, as part of a list of pardons and commutations for some 273 people. She will apparently be freed on May 17.

"Mr. Assange welcomes President Obama's decision to commute Chelsea Manning's sentence," said Barry Pollack, Assange's legal representative in the U.S., in a statement published in U.S. media.

"Whistleblowers like Chelsea Manning serve the public interest. She should never have been prosecuted and sentenced to decades in prison," he said.

Whistleblower website WikiLeaks had said last Thursday that Assange, who has sought asylum in the Ecuadorian embassy in London and faces a U.S. extradition request from Sweden on sexual assault charges, would hand himself over to the U.S. if Manning were freed.

"Thank you to everyone who campaigned for Chelsea Manning's clemency. Your courage & determination made the impossible possible," Assange said in a WikiLeaks tweet after the announcement, without weighing in on his pledge.

The 29-year-old army private, formerly known as Bradley Manning, made international headlines after releasing thousands of classified U.S. military documents to WikiLeaks.

The decision was made because Manning received a harsher sentence than other people convicted of similar crimes and had "accepted responsibility, expressed remorse and began serving the sentence that was handed down," a U.S. official said Tuesday.

"The president still thinks [Manning's] actions were criminal and were not good for the country. They harmed our national security," said the official, who spoke to reporters on the condition of anonymity.

Obama did not say whether questions about the treatment of the transgender soldier had played a role in the decision.

The former intelligence analyst, who took the documents while working in Iraq, was jailed for espionage in 2013.

Later that year, Manning was found guilty on 20 of 22 charges that had been brought against the then 25-year-old soldier, but was acquitted on the most serious charge of knowingly aiding the enemy in the WikiLeaks case.

Manning has admitted to lifting an estimated 700,000 classified diplomatic and military documents from the U.S. government system and offering them to WikiLeaks.

The classified documents included higher estimates of civilian deaths in Iraq than officially announced and the voice recording of a helicopter gunner shooting at targets that later turned out to be Reuters journalists. She is currently being held in a prison at the Fort Leavenworth military base in the U.S. state of Kansas. Barry Pollack's Tuesday statement demanded that Manning be released "immediately."

"Likewise, publishers of truthful information serve the public interest, promote democracy, and should not be prosecuted," the statement said.

Also Tuesday, Obama pardoned retired Marine General James Cartwright, who had pled guilty to lying to investigators about providing a reporter with classified information about Iran's nuclear program.