Forty-three immigrants from Ethiopian and Somali were found dead in a truck in central Tanzania, having perished from asphyxiation, the deputy interior minister said.
"They died of suffocation and had no food," Pereira Silima said on Tuesday.
"There were more than 100 people in the truck," a local administration official told AFP news agency.
The bodies were discovered in Dodoma province, about 400km west of Dar es Salaam.
Tanzania's state television said the bodies were thrown off the truck and dumped in the bush after the driver of the truck realised some of the people he was smuggling had perished. Those who survived are receiving medical treatment and being questioned by police.
In December, 20 Somali immigrants were found dead in Tanzania.
Foreign ministry spokesman Isaac Nantanga said at the time that an increasing number of Ethiopians and Somalis were crossing the country to make their way to South Africa, the continent's top economy.