|A lucky few have been released|
In the last 10 days one detainee attempted to kill himself for the first time, while another made a repeat attempt. Neither man was injured and both received medical and mental evaluation, a Pentagon spokeswoman said.
Eighteen detainees have tried to kill themselves at the US detention camp in Cuba - mostly by hanging.
There have been 27 separate suicide attempts at the Guantanamo facility since it was opened in January 2002.
Roughly 680 prisoners are being held at Guantanamo. "There's definitely concern in terms of reducing the number of attempts," the spokeswoman said, adding: "It's not an easy situation."
No-one has died, although one detainee who attempted suicide has been hospitalised for months. He is still under medical supervision, but has come out of a coma and is doing better.
Human rights groups have criticised the US for the conditions under which the prisoners are held, adding that interrogation techniques used there might include torture.
The US has used the Guantanamo base to hold non-US citizens, including suspected members of Al-Qaeda.
The Pentagon has refused to identify them, has not brought charges against any, and has barred them from contacting lawyers. The Pentagon is in the final stages of planning military trials for at least some of the prisoners.
The spokeswoman claimed that the detainees were being held in humane conditions, displaying pictures of the facilities in which they are being held. "It's not a Hilton by any means. But they have a personal bathroom facility and water and a bed. They're not sleeping on the floor," she said.
The Pentagon has taken several steps to try prevent further suicide attempts. Guards have received additional training, authorities have established a mental health unit that provides follow-up care and there is closer supervision by medical staff, the spokeswoman said.