In a statement released Tuesday night, IOM confirmed that 14 survivors were rescued by local authorities and are being treated at a local hospital.
The survivors told local authorities that they were Ethiopians headed to South Africa.
The truck driver and his assistant, both Mozambicans, were arrested, provincial immigration spokesman Amelia Direito told AFP.
She said the driver told police he had been promised 30,000 meticais (about $500, 460 euros) to transport the men.
Police have launched a manhunt for “the intermediary who facilitated the illegal entry of the Ethiopians into the country,” Direito added.
Temperatures in Tete have been above 90 degrees Fahrenheit this week.
None of the men were carrying identification, and IOM is working to provide assistance to the survivors.
South Africa is home to more than 4 million migrants and close to 300,000 asylum seekers and refugees according to the latest U.N. statistics.