Officials say desert kidnaps require huge resources
Algerian police have found a vehicle thought to belong to some of the European tourists who have gone missing in the desert.
Officials say the blue four-wheel-drive Iveco car found near the south-eastern town of Illizi may be that used by a German couple who disappeared on 8 March.
Separately Colonel Massaoud Benboudria, who is leading the search, said he was "personally convinced" that all the tourists were alive and might be in another country.
More than 1,000 Algerian troops have been deployed to look for the 31 tourists - from Austria, Germany, Switzerland, Sweden and the Netherlands.
Some of the travellers - who were in seven separate groups - have not been heard from since February.
'No evidence' of kidnap
Colonel Benboudria told El Watan newspaper on Sunday that there was no evidence to support speculation that the tourists had been abducted by Islamic rebels.
I am personally convinced that the tourists are alive and could even be outside of Algeria - I think we will find them
"Terrorists don't keep hostages," he said. "They usually kill them for media effect or use them as a bargaining tool."
He added that it would require huge resources to keep such a large group hostage in the Sahara.
There was no evidence to suggest they had been murdered either, he said.
Media reports in Algeria have suggested that militant groups linked to Osama Bin Laden's al-Qaeda network could be behind the disappearances.
Attention has focused on militant Islamist leader Mokhtar Belmokhtar, who operates in the region.
Colonel Benboudria said he thought the tourists had got lost in violent sandstorms.
Algerian tourism officials have suggested that the tourists brought their fate on themselves because they had travelled
without the help of guides who know the desert terrain.
The missing tourists all used Global Positioning Systems (GPS)
which rely on satellites to help travellers establish their exact location.
Some of the tourists left a message in the desert two weeks ago saying they were alive.
The tourists comprise 15 Germans, 10 Austrians, four Swiss nationals, a Dutchman and a Swede.