Advocates for the prisoners blamed the Bush administration for the deaths, which they said would inflame the global Muslim community's anger.
Two Saudis and a Yemeni hanged themselves with clothes and bed sheets in maximum security cells, the first captives to die at Guantanamo since the US began sending suspected al-Qaeda and Taliban captives there in 2002.
A US State Department Deputy Assistant Secretary, Colleen Graffy, has told the BBC the deaths were part of a strategy and "a tactic to further the jihadi cause", but taking their own lives was unnecessary.
Speaking to the BBC's Newshour program, Ms Graffy said the three men did not value their lives nor the lives of those around them, and described it as a PR stunt.
Detainees had access to lawyers, received mail and had the ability to write to families, so had other means of making protests, she said, adding it was hard to see why the men had not protested about their situation.
Hicks “desperate for contact”
The only Australian held at Guantanamo Bay, David Hicks, was described by his lawyer as desperate for human contact.
Major Michael Mori said David Hicks, who has been couped up in the Cuban detention centre for more than four years, was in poor health, suffering weight loss and continuing signs of depression.
"I found him very desperate for human contact," said Mr Mori, who visited Mr Hicks last week.
"You could just tell when I first got to see him he was just so hungry to interact with another human being," he told Australian Broadcasting Corp. radio.
Prime Minister John Howard, who says Mr Hicks must face US justice and has refused to work for his release, said the detainee had received a consular visit two weeks ago, which raised no concerns.
"I have been told that he received a consular visit about two weeks ago and the report from that consular visit was positive," Mr Howard, a steadfast ally of US President George W. Bush, told reporters.
"Driven by despair"
Rear Admiral Harry Harris, the commander of Guantanamo Bay, described the suicides as an act of warfare.
"They are smart, they are creative, they are committed," he said of the prisoners.
"They have no regard to life, neither ours nor their own. And I believe this was not an act of desperation, rather an act of asymmetric warfare waged against us."
Ken Roth, head of Human Rights Watch in New York, told the BBC the men had probably been driven by despair.
"There's no end in sight. They're not being brought before any independent judges. They're not being charged and convicted for any crime."
Saudi Arabia's interior ministry identified the two Saudis as Manei al-Otaibi and Yasser al-Zahrani but gave no further details.
Pentagon documents show Zahrani was 21, meaning he was sent to Guantanamo as a teenager.
Guantanamo holds about 460 foreigners captured during the US-led war to oust al-Qaeda from Afghanistan after the September 11 attacks.
Call for closure
The US administration calls them dangerous men who would launch deadly attacks on America and its allies if released.
But President George W Bush said on Friday he would like to empty Guantanamo and is working to repatriate many of the detainees.
Senator Jack Reed, a Democrat from Rhode Island, said the US must find another way to keep the Guantanamo prisoners off the streets.
"There are some ruthless and fanatical terrorists that are in our custody and we just can't turn them loose," Sen Reed told CNN.
Before the weekend, 23 prisoners had tried to kill themselves in 41 suicide attempts at the camp.
They have been held for more than four years, most without charges and face indefinite detention with none of the rights afforded prisoners of war or criminal suspects in the US justice system.
Shafiq Rasul, a British former Guantanamo prisoner who won a US Supreme Court case upholding the inmates' now-curtailed right to challenge their detention in the US courts in 2004, said he witnessed suicide attempts while held there.
"There were individuals who had just had enough, couldn't take any more, were going crazy, who would attempt to kill themselves," he told Sky Television.
Britain, Germany and other US allies have joined a chorus of rights groups that have urged Washington to close the camp.
"If it is perfectly legal and there is nothing going wrong there, why don't they have it in America?" Britain's Constitutional Affairs Minister, Harriet Harman, said on BBC television.
The US Supreme Court is expected to rule this month on the legitimacy of special military tribunals set up to try those charged with war crimes, and to clarify what rights the prisoners have in US courts.
Pre-trial hearings had been scheduled at Guantanamo this week for one of the 10 men charged so far before the tribunals, but the hearings were cancelled due to the suicides.