But he said Germany would consider any US request to accept some of the detainees.
"We would need to, and want to, examine this issue when the United States has made clear what its specific plans and timeline are," Steg said.
"[But] if we begin to review such closure plans and take a stance, then it can only be in a European context based on a discussion with all member states," he said, adding that Germany would reject any "side deals, swaps or conditions" put forward by Washington linked to handing over prisoners.
In a letter to European Union counterparts this month, Luis Amado, the Portuguese foreign minister, said the EU should help the US close Guantanamo by taking in former detainees.
|Germany said it would reject any deals or swaps put forward linked to prisoners [AFP]
Frank-Walter Steinmeier, the German foreign minister, has ordered ministry officials to begin preparing for a possible request to take in former Guantanamo prisoners, a spokesman said, adding that German officials met with human rights activists and lawyers for detainees last month.
"Efforts to close Guantanamo must not be allowed to fail" because of difficulty finding countries to accept former inmates, Ploetner said.
Guenter Nooke, the German government's senior human rights official, launched a national debate last week when he called for Berlin to take in some of the 17 ethnic Uighurs from the western Chinese region of Xinjiang held at Guantanamo.
The group has been in limbo at Guantanamo - despite being cleared for release by the US government - because officials cannot find a country willing to take them.
The men cannot be returned to China because of fears they may be tortured there as political dissidents, US officials said.
Call for asylum
Robert Gates, the US defence secretary, who will be staying on under the Obama administration, said last week that an obstacle to quickly closing the site has been getting countries to take prisoners who are no longer considered a threat.
Rights groups have called on EU countries to offer asylum to former detainees.
Steg said there were no German inmates at Guantanamo. In August 2006 Germany took back Murat Kurnaz, a Turkish national, who had been held at Guantanamo since January 2002.
After his return, Kurnaz, who was born and raised in Germany, accused the German government of rejecting a US offer to release him in 2002 despite its vocal opposition to the Guantanamo jail.
He has also said he was beaten by German special forces in Afghanistan while he was being held by the US military in late 2001, before his transfer to Guantanamo.
The charges were investigated by German authorities, but never officially substantiated.
The Guantanamo Bay detention camp, which currently holds about 250 inmates, was opened in early 2002 at a US naval base on the southeastern tip of Cuba as a way to hold detainees beyond the reach of US courts.