"Tunisian security forces have collectively expelled several hundred Black African migrants and asylum seekers, including children and pregnant women, since July 2, to a remote, militarized buffer zone at the Tunisia-Libya border," Human Rights Watch said.
"Many reported violence by authorities during arrest or expulsion," the New York-based watchdog said in a statement.
HRW's Lauren Seibert urged Tunisia's government to "halt collective expulsions and urgently enable humanitarian access to the African migrants and asylum seekers already expelled to a dangerous area."
The people expelled were of many African nationalities:
Ivorian, Cameroonian, Malian, Guinean, Chadian, Sudanese, Senegalese, and included 29 children and three pregnant women, HRW said.
The rights group said migrants it interviewed alleged "several people died or were killed at the border area" between Sunday and Wednesday, "some shot and others beaten" by Tunisian security forces.
"They also said that Libyan men carrying machetes or other weapons had robbed some people and raped several women," HRW reported, adding it was unable to independently confirm the accounts.
"Not only is it unconscionable to abuse people and abandon them in the desert, but collective expulsions violate international law," said Seibert.
HRW called on the government in Tunis to "investigate and hold to account security forces implicated in abuses."
The Tunisian interior ministry did not respond to requests for comment.
This report was sourced from Reuters and Agence France-Presse.