Some reports suggest the death toll may be as high as 73, and 110 people have suffered burns.
It happened in Tete province near the border with Malawi, where the truck was carrying petrol from the coast.
A government statement said that people were trying to siphon fuel from an overturned truck when heat caused it to explode.
It said government officials would be sent to the region to investigate the incident, and many of the injured had gone to hospital.
More than 70 people have been killed in a fuel truck explosion in Mozambique, government officials say.