Angela Merkel is looking to improve relations with the US
The US has rejected a call by the German Chancellor, Angela Merkel, for the closure of its detention camp at Guantanamo Bay in Cuba.
State department spokesman Sean McCormack said the camp kept society safe from very dangerous people who would fight the US if released.
Chancellor Merkel said the camp "should not exist", days before her first visit to the US since taking office.
She said different ways should be found to deal with prisoners.
Human rights campaigners have expressed growing concern about the treatment of inmates at Guantanamo Bay.
The US has denied allegations that it tortures prisoners at the camp.
Mr McCormack said everybody hoped there would come a point where Guantanamo would not be needed, but that point had not come yet.
"Guantanamo serves a purpose and it's there for a reason," he said.
"It keeps people who are very dangerous away from civilised society. Make no mistake about it; if these people were released, they would be right back in the fight."
Mrs Merkel's comments come as Germany hopes to improve relations with the US, which were strained after former Chancellor Gerhard Schroeder opposed the Iraq war.
At a news conference on Saturday, Mrs Merkel defended her comments, but said she would not demand the immediate closure of the camp when she held talks with US President George Bush next week.
Earlier, Mrs Merkel told the German magazine Der Spiegel: "An institution like Guantanamo can and should not exist in the longer term.
"Different ways and means must be found for dealing with these prisoners."