At least 40 schoolboys were killed on Monday when a crowded school bus skidded off the road and crashed into a canal in Bangladesh's Chittagong district, 136 miles from the capital, Dhaka.

The Calcutta Telegraph reported that the death toll was likely to rise, with dozens more boys feared trapped in the submerged bus.

The children were understood to have been returning from a soccer tournament when the accident took place.

There were up to 70 boys aged between 6 and 11 years old aboard the bus when it crashed, Al Jazeera reported.

The network's correspondent in Dhaka, Nicolas Haque, said:

According to several witnesses, the boys were singing and dancing on board the truck, which skidded off the muddy road and turned as it plunged into the canal.

Officials said the number of dead may be higher than reported, because relatives of the children may removed some bodies before an official count took place.

A Chittagong district police officer told the BBC that 40 bodies had been recovered.

Each year in Bangladesh, an estimated 12,000 people die in road accidents, due to poor road conditions, old vehicles and speeding.