Ban Ki-moon was echoing an appeal by his predecessor, Kofi Annan, who urged President George W. Bush's administration in February 2006 to shut down Guantanamo as soon as possible.
"I understand that today is the fifth anniversary of Guantanamo's prison," Ban told his first news conference since taking the reins of the U.N. on Jan 1. "Like my predecessor, I believe that prison at Guantanamo should be closed."
"I also remember that President Bush himself has said he would like to close it," the new secretary-general said.
The U.S. military is holding about 395 men at the military base in Cuba on suspicion of links to al Qaeda or the Taliban, including about 85 who have been cleared to be released or transferred to other countries. The military says it wants to charge 60 to 80 detainees and bring them to trial.
The base began receiving terror suspects on Jan. 11, 2002, and its treatment of the detainees has come under strong criticism from human rights groups.
Annan called for Guantanamo's closure after a U.N.-appointed independent panel said in a report that the United States must close the detention facility "without further delay" because it is effectively a torture camp where prisoners have no access to justice.
Annan said he did not necessarily agree with everything in the report, but "the basic premise, that we need to be careful to have a balance between effective action against terrorism and individual liberties and civil rights, I think is valid." He said he supported the panel's opposition to people being held "in perpetuity" without being charged and prosecuted in a court where they had the opportunity to explain themselves.
Ban was asked whether he would raise the issue of closing Guantanamo during a meeting with Bush at the White House next week.
"I'm going to visit Washington, D.C., in my capacity as the new secretary-general at the invitation of president Bush who is the leader of the host government," he said.
He then stated his belief that Guantanamo should be closed, without elaborating.
Ban has stressed, however, that protecting human rights is one of the three pillars of the United Nations along with ensuring peace and security and promoting development. He has also stressed the importance of justice.
Ban ran into trouble on his first day of work as secretary-general on Jan. 2 over Saddam Hussein's execution when he failed to state the U.N.'s opposition to the death penalty and said capital punishment should be a decision of individual countries.
His spokeswoman, Michele Montas, said on Jan. 3 that Ban backed the U.N. human rights chief's appeal to Iraq's president to refrain from executing two of Saddam's co-defendants and believes that the 192 U.N. member states should move toward the abolition of capital punishment, the U.N. spokeswoman said Wednesday.
At Thursday's press conference, Ban said he wanted to clarify his position on the death penalty.
"I believe that life is precious and must be protected and respected and that all human beings have the right to live in dignity," he said.
"International law affirms these value. I recognize the growing trend in international law and in national practice toward a phasing out of the death penalty. I encourage that trend," Ban said.