More than 600 migrants forced out of Tunisia's port of Sfax to the desert borderlands are being sheltered and given humanitarian aid, the Red Crescent has said.
Smaller groups of people remain stranded near the Algerian and Libyan border.
Hundreds of migrants from sub-Saharan countries fled or were forced out of Sfax after racial tensions flared following the July 3 killing of a Tunisian man in an altercation between locals and migrants.
Sfax is a North African departure point for many migrants from impoverished and war-torn countries hoping to travel to Europe.
Many of those forced to leave Sfax were left to fend for themselves in harsh desert conditions near Tunisia's borders.
Abdellatif Chabou, president of the Tunisian Red Crescent, told AFP on Wednesday that the charity had been authorised to pick up hundreds of migrants left without water or food in the militarised zone of Ras Jedir, on the Libyan border.
He said the organisation had provided shelter to “630 in total” between Sunday and Monday – a figure which could increase in the coming days.
The Red Crescent said it was feeding the migrants and had brought 400 mattresses from Tunis to equip the schools where they are now being sheltered.
NGOs said they are concerned about the fate of dozens of other migrants, estimated by Human Rights Watch to be around 150 to 200, along Tunisia's western border with Algeria.
“We are receiving several messages and calls from people who were deported to border areas with both Algeria and Libya,” Hiba, a member of The Alarm Phone organisation, an NGO that helps bring attention to migrants in distress, told The National, without revealing her full name.
“These people do not have access to food, water or protection from the elements and as we keep losing contact with many of them. We no longer know if some groups are still alive or not.”
The Alarm Phone said that it has notified both Tunisian authorities and the UN's affiliated refugees and migration bodies, however, it has received no response.