An injured man is carried from the scene as a petrol tanker burns in the background in Morogoro, Tanzania.

Tanzania was in mourning on Sunday, preparing to bury the dead after 69 people perished when a crashed fuel tanker exploded as crowds rushed to syphon off leaking petrol.

President John Magufuli declared a period of mourning through Monday following the deadly blast near the town of Morogoro, west of Dar es Salaam.

He will be represented at the funerals by Prime Minister Kassim Majaliwa, an official statement said.

Destroyed motorbikes and debris after a petrol tanker exploded in Morogoro, Tanzania, on Saturday.

The burials will start Sunday afternoon, Parliamentary Affairs Minister Jenista Mhagama announced during the morning after relatives identified the dead.

"We're currently mourning the loss of 69 people, the last of whom died while being transferred by helicopter to the national hospital in Dar es Salaam," Majaliwa told residents in comments broadcast on Tanzanian television.

The number of injured stood at 66, he said.

Thirty-nine seriously hurt patients had been taken to hospital in Dar es Salaam while the others were being treated in Morogoro, 200 kilometres (125 miles) west of the economic capital of Tanzania.

Footage from the scene showed the truck engulfed in flames and huge clouds of black smoke, with charred bodies. The burnt-out remains of motorcycle taxis lie scattered on the ground among scorched trees.

Victims burnt after a fuel tanker exploded receive treatment at the Morogoro referral hospital in Morogoro, Tanzania. Reuters

A video posted on social media showed dozens of people carrying yellow jerricans around the truck.

President Magufuli called Saturday for people to stop the dangerous practice of stealing fuel in such a way, a common event in many poor parts of Africa.

Magufuli issued a statement saying he was "very shocked" by the looting of fuel from damaged vehicles.

"There are vehicles that carry dangerous fuel oil, as in this case in Morogoro, there are others that carry toxic chemicals or explosives, let's stop this practice, please," he said.

Last month, 45 people were killed and more than 100 injured in central Nigeria when a petrol tanker crashed and then exploded as people tried to take the fuel.

Among the deadliest such disasters, 292 people lost their lives in the eastern Democratic Republic of Congo in July 2010, and in September 2015 at least 203 people died the South Sudan town of Maridi.

Agence France-Presse