Military and civilian lawyers for prisoners at the Guantanamo naval base urged U.S. Defense Secretary Chuck Hagel to improve conditions for detainees, putting more pressure on the Obama administration to make good its promise to close the camp.
The plea from 18 lawyers representing "high-value" prisoners came before a speech by President Barack Obama on Thursday when he will address counterterrorism measures such as drone strikes and closing Guantanamo.
Obama is struggling to emerge from a series of domestic scandals that critics say show his administration is secretive and bullies the media and political opponents.
Thursday's speech at the National Defense University in Washington is meant as an effort to show he is eager to protect civil liberties.
Calls on Obama to close the Guantanamo Bay camp have risen as a hunger strike at the U.S. naval base in Cuba lingers. Prisoners are in their fourth month of the strike to protest the failure to resolve their fate after 11 years of detention.
More than 100 people have joined the protest and 31 have lost so much weight that they are being force-fed liquid nutrients through tubes inserted into their noses and down to their stomachs to keep them alive.
It is the largest hunger strike at the camp in several years.
"While the hunger strike continues to increase in scope and severity, there is much you can do, right now, to improve the quality of life for all the prisoners," the lawyers said in their letter to Hagel, which was dated earlier this week and seen by Reuters on Wednesday.
They said that detention practices at Guantanamo violated the Geneva Conventions, the international treaties that govern the treatment of captives during armed conflict.
Camp officials spy on lawyers' supposedly private meetings with their clients, seize confidential legal documents and harass prisoners with daily cell shakedowns and degrading bodily searches, the lawyers said.
Obama has promised repeatedly to close Guantanamo, but opposition in Congress, which controls funding for transferring detainees out of the camp, has stopped him.
He will call again for Guantanamo to be emptied when he speaks on Thursday and will announce a number of specific steps to advance that goal, a White House official said.
As part of its push for transparency, the administration acknowledged for the first time on Wednesday that it had killed four Americans, including militant cleric Anwar al-Awlaki, who died in drone strikes in Yemen and Pakistan.
One effort that Obama might make on Guantanamo is to name an official to head the transfer of detainees. Of the 86 prisoners cleared for transfer or release, 56 are Yemenis.
"Keeping (Guantanamo) open is not efficient. It's not effective. And it's not in the interests of our national security. And I think senior members of the military have testified to that fact," White House spokesman Jay Carney told a briefing.
The Wall Street Journal reported on Wednesday that the Obama administration was set to restart transfers of detainees from Guantanamo in the coming weeks, starting the process of closing the camp down.
The lawyers who wrote to Hagel represent the captives previously held in secret CIA prisons, some of whom are facing death penalty trials by military commission for allegedly plotting the September 11 hijacked plane attacks and the deadly 2000 bombing of a U.S. warship, the USS Cole, off Yemen.
Army Captain Jason Wright, a lawyer for alleged September 11 mastermind Khalid Sheikh Mohammed, said that unlike other prisoners, the former CIA captives were held in isolation tantamount to solitary confinement and prevented from contacting their families.
The U.S. government maintains it has the right to hold them forever even if they are acquitted at trial and to keep holding other captives whom it does not intend to try.
"So now these men are facing the indefinite prospect of detention for the remainder of their lives," Wright said.
He said Mohammed "has been observing a religious fast for quite some time," but apparently was not among those being force-fed.
Nearly 800 men were rounded up after the September 11 attacks in 2001 and held at Guantanamo on suspicion of involvement with al Qaeda and the Taliban. More than half of the 166 remaining prisoners have been cleared for transfer or release, but efforts to repatriate them have stalled.
Shutting Guantanamo is fraught with difficult legal and political questions.
An aide to House Armed Services Chairman Republican Howard McKeon said that if Obama was trying to close Guantanamo, he needed to give "concrete answers on what the president intends to do with those terrorists who are too dangerous to be released but cannot be tried; how he would ensure that transferred detainees can't rejoin the fight; and what he will do to detain and interrogate new terrorist captures or those very dangerous terrorists still held in Afghanistan."
Camp officials say 103 detainees were taking part in the hunger strike. One detainee was in the hospital but did not have life-threatening conditions, a Guantanamo spokesman, Army Lieutenant Colonel Samuel House said on Wednesday.
"The biggest difference between this hunger strike and the ones previous is the ones earlier were for living conditions and other tangibles, whereas this one focuses on indefinite detention," House said.
An investigation ordered by the Obama administration in 2009 found that the Guantanamo prison complied with the humane treatment standards required by the Geneva Conventions.
But the lawyers said conditions had worsened during the past year and accused the current detention camp commanders of waging a campaign to dehumanize the prisoners through isolation, force-feedings and collective punishment of hunger strikers.
House said camp officials do not comment on detainee allegations made through their attorneys but provide safe, humane, legal and transparent care of those detained there.