WASHINGTON — A US soldier accused of leaking a military video from Iraq and suspected in the release of thousands of secret documents on the Afghan war has been moved to a US military jail, the Pentagon said on Friday.

Private First Class Bradley Manning arrived at Quantico Marine Base in Virginia late on Thursday, the Pentagon said, after his court martial proceedings were transferred from Camp Arifjan, Kuwait.

Manning is facing four charges related to the leak to the website WikiLeaks of a video showing a US Apache helicopter strike in Baghdad in July 2007 that killed several people.

He now is also suspected of possible involvement in the bombshell leak to the same website of tens of thousands of classified documents related to the war in Afghanistan.

The Pentagon and the FBI have launched an investigation into the case while US leaders and Afghan President Hamid Karzai have condemned the leak, citing fears that Afghan informants named in some of the documents could now be at risk.

Top military officer Admiral Mike Mullen on Thursday expressed outrage over the leak, saying the founder of the Wikileaks webiste, Julian Assange, may have blood on his hands.

"Mr Assange can say whatever he likes about the greater good he thinks he and his source are doing, but the truth is they might already have on their hands the blood of some young soldier or that of an Afghan family," he said.

Assange has defended the release of the files, saying he hoped it would spark a debate about the war and that his site had checked for named informants before distributing the papers.

The website founder has also called Manning a "political prisoner" and alleged the United States kept him under detention in Kuwait to render him effectively "incommunicado."

The graphic video of the helicopter attack was posted on the Internet by WikiLeaks in April this year, prompting an international outcry and renewed demands for compensation from the victims' families.

In addition to leaking the video, Manning, 22, is accused of illegally downloading more than 150,000 diplomatic cables, 50 of which he is alleged to have transmitted unlawfully to the danger of US national security.

US officials could not confirm a report by The Wall Street Journal that authorities have evidence linking Manning to the latest secret US material released by WikiLeaks -- 92,000 classified US military files on the Afghan war between 2004 to 2009.

In a statement, the Defense Department said his transfer to the United States had been requested "due to a potentially lengthy pre-trial confinement because of the complexity of charges and an ongoing investigation."