LONDON, JUNE 24

Fifteen children have drowned in flash floods that swept through Bangladesh with another 3.5 million urgently needing clean drinking water as the risk of waterborne diseases grows, UNICEF's country representative said on Friday.

"That's a staggering number of children and an increase over the last couple of days. Huge areas are fully underwater and are disconnected from safe drinking water and food supplies. Children need help right now," Sheldon Yett said.

Government and aid agencies have rushed to provide relief including water and other supplies after flash flooding across a quarter of the South Asian nation.

The floods have also disrupted health facilities, shut schools and disrupted malnutrition treatment for hundreds of children, Yett told a briefing in Geneva.

Cases of diarrhoea have risen to 2,700 as of the middle of this week, he added.

Authorities in Bangladesh and neighbouring India have warned of a risk of a disease epidemic. In total, more than 4.5 million people have been stranded and dozens killed in Bangladesh, many in the worst flooding in the Sylhet region in the northeast for more than 100 years.

In the eastern Indian state of Assam, Indian air force helicopters have been deployed to drop food and other supplies to cut-off communities.