At least 16 migrants from sub-Saharan Africa died on Saturday when the vehicle they were travelling in plunged into an irrigation canal, state news agency MAP reported.
The agency said 17 other “sub-Saharan Africans looking to become illegal immigrants” were injured and transported to hospital after the accident on a minor road near the Spanish territory of Melilla.
Local authorities quoted by MAP said the driver fled the scene and an investigation had been launched into the crash.
Local NGO the Moroccan Association of Human Rights said the death toll was at least 19 and added around 50 people had been travelling in the vehicle.
It said the vehicle was “often used by traffickers to transport migrants”.
Melilla is one of two Spanish territories attached to northern Morocco that mark the European Union’s only land borders with Africa.
The International Organization for Migration says that 1,605 migrants crossed by land into Spain in the first four months of this year.
The Moroccan authorities said they stopped 89,000 “attempts at illicit immigration” last year, including some 29,000 by sea.