At least 38 people were killed in a bus crash in southeastern Brazil on Saturday, officials said, in what President Luiz Inacio Lula da Silva called a "terrible tragedy."

The accident in Minas Gerais state, involving a bus that caught fire in the collision, is the worst seen on Brazil's federal highways since 2007, according to police data cited by local media.

In their latest report, civil police confirmed 38 fatalities with eight people hospitalised.

Conflicting accounts of the accident have emerged: firefighters initially said the bus at around 3.30am had blown a tyre near the town of Lajinha, causing the driver to lose control of the vehicle and hit a truck. Another vehicle also hit the bus from behind, officials said, but its occupants survived.

However, firefighters later cited witnesses as saying that a granite block being transported by the truck fell onto the bus, causing the accident.

After the crash, the bus, which had been making its way from Sao Paulo to Vitoria da Conquista, in the northeastern Bahia state, caught fire.

The death toll has crept upward throughout the day, with a spokeswoman for the local fire department earlier telling AFP that "it was not yet possible to specify the exact number due to the state of the bodies."

The fire department, upon removing charred remains, said earlier that some of the victims had been trapped inside.

In a video released Saturday morning, Lieutenant Alonso Vieira Junior, with the Minas Gerais fire department, said a crane would be needed to clear the wreckage, and that "there are still more victims to be removed."

Among the dead are the bus driver and at least one child.

Lula took to social media to offer his prayers for "the recovery of the survivors of this terrible tragedy."

"I am deeply sorry," he said, offering condolences to the families of the victims.

The governor of Minas Gerais said he was working "so that the families of the victims are cared for, to deal with this tragedy in the most humane way possible."

At the end of November, a bus accident in the state of Alagoas, in the northeast, left 17 dead when it plunged into a ravine while traveling on a remote mountain road. 

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