Former US President Bill Clinton has become the latest and most prominent American figure to say Guantanamo should be "closed down or cleaned up".
Bill Clinton says abuse reports put US troops at greater risk
Interviewed by the Financial Times, he said it was time to put an end to the flow of abuse reports from the prison.
If the treatment of terrorist suspects changes the fundamental character of the US, it should be avoided, he added.
A heated debate on the Cuba-based prison is raging in Washington after Senate hearings on the issue last week.
"[Guantanamo] either needs to be closed down or cleaned up," Mr Clinton said.
"It's time that there are no more stories coming out of there about people being abused."
Apart from the ethical questions raised by the treatment of prisoners at the centre, there were also "two huge practical problems", the Financial Times quoted Mr Clinton as saying.
Firstly, abuse cases at detention centres were damaging to the reputation of US and British troops in the world, thereby putting soldiers at risk.
Secondly, abuse could easily lead to prisoners confessing to crimes they had never committed.
Mr Clinton praised "very outspoken" military officers who voiced criticism of prisoner abuses at Guantanamo on those grounds.
"There's one thing I'd like international leaders to know about America," he said.
"The vast majority of our military personnel are opposed to the abuse practices on moral ground because it makes the people serving under them more vulnerable, and because you can get anyone to say anything if you beat them up badly enough."
With regard to prisoners being held indefinitely, the former president said that while he was in office, a law allowed terrorist suspects to be detained beyond the normal length of time without trial.
But he added that the issue was a big dilemma.
"I still don't think you can just hold these people forever," he said.
"I think sooner or later you've got to move or let them go... it is just inimical to a free society."
Recent critics of the high-security detention centre include former President Jimmy Carter and Democratic Senator Dick Durbin, who last week compared interrogation practices at the prison to those used under Hitler and Stalin.
Amnesty International has branded it "the gulag of our times".
But US Vice-President Dick Cheney said there were no plans to close the prison, describing the detainees there as "bad people" and "hardcore".
Many of the 500 men held at the facility have been there for three years without trial.