The International Organization for Migration (IOM) said on Sunday that the bodies of 18 west African migrants have been found in the Sahara Desert near Arlit in Niger.
Thousands of poor people are making a dangerous journey through inhospitable terrain in the Sahara in an attempt to reach the Libyan coast where they hope to start another dangerous journey 2,340 km (1,500 miles) across the Mediterranean sea by boat to Europe.
"This case is indicative of the difficulties of these journeys, even before reaching the boats in Libya," Giuseppe Loprete, the head of IOM in Niger, said in emailed comments.
"We have to ask ourselves how many people have died [are dying] in the desert even before making it [the trip] to the Mediterranean. We don't think this is an isolated case but without a systematic collection of information or without a 'rescue' operation we will never know how many migrants could be possibly missing."
The increasing number of migrants has been reported by coast guards, navies, local authorities and aid organisations.
The IOM has said that increasing numbers of west Africans have taken the trip this year despite the fact that most of the migrants are Syrian and Eritrean nationals.
Loprete said controlling the desert as an attempt to prevent the migrant deaths is "nearly impossible."
The 17 men and one woman, found dead, had been travelling from Arlit to Assamaka. They were from at least eight countries - including Mali, Senegal, Ivory Coast and Guinea. The group was traveling in a land cruiser but lost their way in a sandstorm. They ran out of fuel and became stuck in the sand.
An Algerian man, one of the group, captured a camel and tried to reach the town of Assamaka, which is close to Niger's border with Algeria, in order to get water and help. However he fell off the animal and died. The group were found eight days later, after they had died of dehydration around June 3, according to the IOM staff in Niger.