A top US official has slammed the harsh treatment of a soldier at the center of the WikiLeaks row as "ridiculous" and "counter-productive," comments dismissed Friday by President Barack Obama.

Obama told a White House press conference that the conditions of Private First Class Bradley Manning's detention are "appropriate" and meet the country's "basic standards."

He was commenting after US State Department spokesman Philip Crowley, in a highly unusual departure from diplomatic language, suggested during a forum on new media and diplomacy at the Massachusetts Institute of Technology that there were tensions over Manning's detention.

Asked for his opinion about the United States "torturing" a prisoner in a military brig, Crowley said Manning's treatment by the Defense Department "is ridiculous and counterproductive and stupid," BBC reporter Philippa Thomas wrote on her blog.

"None the less Bradley Manning is in the right place," Crowley reportedly said, adding "there is sometimes a need for secrets" to advance US diplomatic interests.

Crowley did not respond to email queries by AFP about the blog by Thomas who is currently a Nieman Journalism Fellow at Harvard University.

The Cable, Foreign Policy magazine's blog, said Crowley confirmed that he did in fact make the remarks.

"What I said was my personal opinion. It does not reflect an official USG policy position. I defer to the Department of Defense regarding the treatment of Bradley Manning," he told The Cable.

Obama said Friday he had "asked the Pentagon whether or not the procedures that have been taken in terms of his confinement are appropriate and are meeting our basic standards.

"They assure me they are," Obama told White House reporters in a terse response. "I can't go into details about some of their concerns, but some of this has to do with Private Manning's safety as well."

Colonel David Lapan, the Pentagon spokesman, said Manning "is treated in accordance with US law, with DoD (Department of Defense) regulations, with the standards set for all detainees. He has the same rights and privileges."

"He's not treated differently, he's not being treated harshly, he can certainly believe it so," Lapan said.

The Defense Department is making sure he is held safely until his trial takes place, he added.

He said the conditions of his detention are constantly evaluated and could change if required, in line with the law and regulations.

Manning, 23, was arrested in June while he was deployed in Iraq, amid suspicions he had passed a trove of secret US government documents to WikiLeaks, the whistle-blowing website.

Last week the US military unveiled 22 additional charges against him including the serious offense of "aiding the enemy," which carries a potential death sentence. But the army said he would face possible life in prison.

On Thursday, in his first comments about his detention, Manning released a letter via his lawyer charging he is being improperly subjected to unusually harsh conditions at a US military prison.

In his 11-page memorandum, Manning said officials at the Quantico brig in Virginia had abused their discretion in classifying him as at risk of injuring himself and requiring "maximum custody."

He said the prison's own records show he has been a model prisoner and that prison psychiatrists had repeatedly recommended he be removed from "prevention of injury" status.

"Under my current restrictions, in addition to being stripped at night, I am essentially held in solitary confinement," Manning wrote.