HANOI (AFP) - Nine Vietnamese schoolboys from the same class have drowned after jumping into a river in central Vietnam's Quang Ngai province on Friday (April 15), a police official told AFP.

The deaths, which police said were accidental, happened when the victims, all secondary school-students aged 12, were playing in the Tra Khuc river, said Vu Van Duong, deputy head of the provincial police department.

The bodies of the boys, who were all in the same class at the Nghia Ha secondary school, were found next to each other on the riverbed, he said.

"They must have jumped into the water together, right at the same time," he told AFP, adding that the children had ignored warnings from a local woman who had seen them playing by the river.

The boys had been playing in shallow water but the river had recently had a new drainage system added, which made the water up to two meters deep in parts, he added.

Drowning is one of the main causes of child death in Vietnam, especially during the hot summer months and in rural areas.

State media has reported that some 3,500 children die by drowning each year in Vietnam.

Efforts to introduce nationwide swimming lessons in schools have been hampered by a lack of facilities and funding.