The fate of 32 European tourists - including four Swiss - who disappeared in the Sahara desert more than two months ago remains uncertain.
A senior official at the Swiss foreign ministry has just returned from a fact-finding tour to Algeria.
Blaise Godet told a press conference in Bern on Monday that he believed the tourists were still alive but added that it was pointless to indulge in speculation.
"We have no information to lead us to believe that they are dead so we assume that they are alive," Godet told swissinfo.
"They are in a vast, isolated desert and of course it's difficult then to locate the missing tourists and secure their release or freedom," he explained.
He said he had received assurances from the Algerian authorities that they were doing everything possible to protect the lives of the tourists.
Godet admitted that there is a growing sense of frustration that details about the incident are still so sketchy.
"However we understand the complexity of the situation and we have to show patience."
It is widely believed that the tourists were kidnapped and that a ransom is being demanded for their release.
Among the missing tourists are 16 Germans, 10 Austrians, four Swiss, a Dutchman and a Swede.
The tourists were in separate groups and all were travelling without guides.
Meanwhile, Germany's foreign minister, Joschka Fischer, arrived in Algeria on Monday to discuss the whereabouts of the tourists.
Mixed messages have been coming out of Algeria. Last week, Algerian radio quoted Tourism Minister Lakhdar Dorbani as saying that talks were underway with the kidnappers.
This was denied a day later when Interior Minister Yazid Zerhouni insisted "there have been no negotiations or contact with anybody".
The Algerian media have speculated that a fundamentalist Islamic group with links to Osama bin Laden's al-Qaeda network may be responsible for the kidnappings.
The Salafist Group for Preaching and Combat, a militant Islamic group that has been waging a civil war against the Algerian government, is known to operate in the area where the tourists vanished.
swissinfo with agencies
The four Swiss disappeared in February after setting off into desert without a guide.
Sixteen Germans, ten Austrians, a Swede and a Dutchman are also missing.
The tourists are believed to have been kidnapped.
The Swiss foreign ministry says there is reason to believe that the hostages are still alive.