By Pascale Harter
BBC News, Rabat
Morocco is breaking international laws in the way it is handling immigration problems, says the United Nations High Commission for Refugees.
Migrants complain of ill treatment by Moroccan security forces
The UNHCR says Morocco is not allowing them full access to camps where they believe asylum seekers are held.
It says it is very disturbed by reports that Morocco's authorities are holding legitimate registered asylum seekers.
Morocco has denied earlier claims it dumped more than 1,000 Africans in the desert without food or water.
The Moroccan government did allow the BBC into camps, 700km south of the capital, Rabat, claiming only illegal immigrants - and not asylum seekers - were being held there.
But, under armed guard, Africans from war-torn countries such as Liberia, Sierra Leone and the Democratic Republic of Congo showed journalists their UNHCR registration papers and pleaded for help.
"Look at the way they dump me here - suffering in the desert! Please I need help. I want you people to help me from this situation," said a woman.
Many said they were working legally in Casablanca and Rabat when they were rounded up by police, handcuffed and taken by bus to the desert where they were left without water.
They begged the Moroccan government to search the desert for survivors.
Morocco has firmly denied dumping Africans in the desert despite reports by international human rights organisations on the ground.